Devices and methods for increasing blood perfusion to a distal extremity

ABSTRACT

Devices and methods divert blood flow from a first vessel to a second vessel and maintain blood flow in the first vessel. The device includes a first segment and a second segment. The first segment is configured to anchor in the first vessel. The first segment includes a window to allow blood to flow into the first segment, through the window, and distal in the first vessel. The second segment is configured to anchor in the second vessel. The second segment is configured to allow blood to flow into the first segment, through the second segment, and into the second vessel.

INCORPORATION BY REFERENCE

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 CFR 1.57.

BACKGROUND Field

The present application relates to methods and systems for use inpercutaneous interventional surgery. In particular, the presentapplication relates to methods and systems for providing or maintainingfluid flow through body passages such as heart cavities and bloodvessels.

Description of the Related Art

Minimally invasive percutaneous surgery, or “key-hole” surgery, is asurgical technique in which surgical devices are inserted into apatient's body cavity through a small aperture cut in the skin. Thisform of surgery has become increasingly popular as it allows patients toendure less surgical discomfort while retaining the benefits ofconventional surgery. Patients treated by such techniques are exposed tolower levels of discomfort, need for general anesthesia, trauma, andrisk of infection, and their recovery times can be significantly reducedcompared to conventional surgical procedures.

Key-hole surgery can be used, for example, for laparoscopic surgery andto treat cardiovascular diseases. In treating cardiovascular diseases,balloon angioplasty, in which a balloon catheter is inserted into anartery usually near the patient's groin and guided to the patient'sheart where a balloon at a distal portion of the catheter is inflated towiden or dilate an occluded vessel to help restore blood flow to thecardiac tissue, may be used to treat a partially occluded coronaryartery as an alternative to open heart surgery. A tubular supportingdevice (e.g., stent) may be deployed at the site of the blockage toprevent future occlusion (restenosis) or collapse of the blood vessel.The stent may, for example, be an expandable metal mesh tube carried onthe balloon of the balloon catheter, or be self-expanding. Theballoon-expandable stent expands when the balloon is inflated, so thatthe stent pushes against the wall of the blood vessel. The stent isarranged to retain its expanded shape when it reaches its expandedposition, for example by plastic deformation or by means of a mechanicallocking mechanism, so as to form a resilient scaffold or support in theblood vessel. The support structure (e.g., stent) supports and dilatesthe wall of the blood vessel to maintain a pathway for blood to flowthrough the vessel. Self-expanding stents are also available, which areheld in a collapsed state by a suitably adapted catheter for transportthrough the artery and which adopt an expanded state when deployed atthe site of the blockage. The catheter may, for example, include aretaining sleeve which retains the stent in a compressed or unexpandedstate. Upon removal or withdrawal of the sleeve from the stent, thestent expands to support and dilate the wall of the blood vessel.

Balloon angioplasty is not always a suitable measure, for example inacute cases and in cases where a coronary artery is completely occluded.In these instances, the typical treatment is to employ coronary bypass.Coronary bypass surgery is an open-chest or open-heart procedure, andtypically involves grafting a piece of healthy blood vessel onto thecoronary artery so as to bypass the blockage and restore blood flow tothe coronary tissue. The healthy blood vessel is usually a veinharvested from the patient's leg or arm during the course of the bypassoperation. To perform the procedure, the patient's heart must be exposedby opening the chest, separating the breastbone, and cutting thepericardium surrounding the heart, resulting in significant surgicaltrauma.

Conventional coronary bypass surgery is not always an option. Certainpatients are unsuitable as candidates for conventional coronary bypasssurgery due low expectation of recovery or high risk from thesignificant trauma due to surgery, high risk of infection, absence ofhealthy vessels to use as bypass grafts, significant co-morbidities, andexpected long and complicated recovery time associated with open-chestsurgery. For example, factors such as diabetes, age, obesity, andsmoking may exclude a proportion of candidate patients who are ingenuine need of such treatment.

SUMMARY

The present application provides methods and systems for overcomingcertain deficiencies and/or improving percutaneous methods and systems.For example, according to several embodiments, the methods and systemsdescribed herein can improve targeting and localization of therapyadministration, which may advantageously provide treatment viapercutaneous techniques to patients unsuitable for more invasivesurgery. Certain embodiments described herein can provide fluid flow inpassages such as coronary and/or peripheral blood vessels by creating abypass using minimally invasive percutaneous surgical techniques.

In some examples, a launching catheter for targeting a second vesselfrom a first vessel comprises a catheter comprising a proximal portionand a distal portion comprising a flat radiopaque marker. The radiopaquemarker may be rectangular. The catheter may comprise a needle aperture.The catheter may comprise needle configured to extend through the needleaperture.

The distal portion of the catheter may be curved. The marker may notfollow the curvature of the distal portion of the catheter. The needleaperture may be proximal to the marker. The needle aperture may bedistal to the marker. The needle aperture may at least partially overlapthe marker.

The needle aperture may be on a first side of the distal portion of thecatheter. The marker may be on a second side of the distal portion ofthe catheter. The first side may be the same as the second side. Thefirst side may be opposite the second side. A distal end of the needleextended out of the needle aperture may be longitudinally aligned withthe radiopaque marker. The needle may comprise a profile. The needle mayslide through a needle lumen. The needle lumen may comprise acomplementary shape to the profile (e.g., to reduce longitudinalmovement of the needle during advancement of the needle).

The marker may comprise a first radiolucent material and a secondradiopaque material coupled to the first radiolucent material. Thesecond radiopaque material may be coupled to the first radiolucentmaterial by one or more of cladding, plating, chemical vapor deposition,atomic layer deposition, screen printing, coating, adhesion, orsputtering. The second radiopaque material may be polished or flattenedafter being coupled to the first radiolucent material.

A ratio of a length of the marker to a width of the marker may bebetween 1/1 and 5/1.

The marker may have a thickness between 0.001 mm and 1 mm. The markermay have a thickness between 1 nm and 10 μm.

A kit may comprise the launching catheter and a target catheter. Thetarget catheter may comprise an expandable member. The expandable membermay comprise a snare. The expandable member may comprise a mesh. Theexpandable member may comprise a radiopaque material. The targetcatheter may comprise a first radiopaque marker. The target catheter maycomprise a second radiopaque marker longitudinally spaced from the firstradiopaque marker.

In some examples, a launching catheter for targeting a second vesselfrom a first vessel comprises a catheter comprising a proximal portionand a distal portion comprising a needle aperture and a flat rectangularradiopaque marker. The flat rectangular radiopaque marker disappearsunder fluoroscopy upon rotation to provide information about rotationalalignment of the launching catheter. The launching catheter furthercomprises a needle configured to extend through the needle aperture.

In some examples, a catheter comprises a flat radiopaque marker. Thecatheter may be a launching catheter for targeting a second vessel froma first vessel. The catheter may comprise a distal portion comprisingthe flat radiopaque marker. The radiopaque marker may be rectangular.The catheter may comprise a needle aperture. The catheter may compriseneedle configured to extend through the needle aperture. The distalportion of the catheter may be curved. The marker may not follow thecurvature of the distal portion of the catheter. The needle aperture maybe proximal to the marker. The needle aperture may be distal to themarker. The needle aperture may at least partially overlap the marker.The needle aperture may be on a first side of the distal portion of thecatheter. The marker may be on a second side of the distal portion ofthe catheter. The first side may be the same as the second side. Thefirst side may be opposite the second side. A distal end of the needleextended out of the needle aperture may be longitudinally aligned withthe radiopaque marker. The needle may comprise a profile. The needle mayslide through a needle lumen. The needle lumen may comprise acomplementary shape to the profile (e.g., to reduce longitudinalmovement of the needle during advancement of the needle). A kit maycomprise the launching catheter and a target catheter. The targetcatheter may comprise an expandable member. The expandable member maycomprise a snare. The expandable member may comprise a mesh. Theexpandable member may comprise a radiopaque material. The targetcatheter may comprise a first radiopaque marker. The target catheter maycomprise a second radiopaque marker longitudinally spaced from the firstradiopaque marker.

In some examples, a method of aligning a catheter comprises rotating acatheter in a first blood vessel. The catheter comprises a flatradiopaque marker. The rotating is until the marker has a thickness thatindicates rotational alignment of the catheter. The thickness may bevisible under fluoroscopy. The thickness may be less than a certainvalue. The thickness may be indicated by a thin (e.g., minimumthickness) line. The radiopaque marker may be rectangular.

The method may comprise rotating the catheter in the first blood vesseluntil the marker has the thickness (e.g., minimal thickness) underfluoroscopy and is on a side of the catheter. The method may furthercomprise longitudinally advancing the catheter until the marker isproximate a second catheter in a second blood vessel. The secondcatheter may comprise a radiopaque feature visible under fluoroscopy.The radiopaque feature of the second catheter visible under fluoroscopymay comprise an expandable member. The expandable member may comprise asnare. The expandable member comprise a mesh.

The method may further comprise, after rotating the catheter, extendinga needle out of the catheter. Extending the needle out of the cathetermay comprise exiting the first vessel and entering a second vesseldifferent than the first vessel. Aligning the catheter may comprisealigning the needle. Extending the needle out of the catheter maycomprise traversing interstitial tissue between the first vessel and thesecond vessel.

The method may further comprise extending a guidewire through the needleand into the second vessel. The method may further comprise entanglingthe guidewire in a second catheter in the second vessel. Entangling theguidewire may comprise closing an expandable member of the secondcatheter. The method may further comprise moving the second catheter todetect corresponding movement of the guidewire. The method may furthercomprise moving the second catheter to move the guidewire through thesecond vessel.

A catheter system can include a tubular body, and at least one of atargeting system coupled to the tubular body, an expandable member, or afluid injection port.

In some embodiments, a catheter system for identifying a bifurcation ina vessel comprises, or alternatively consists essentially of, a tubularbody, a targeting system coupled to the tubular body, an expandablemember configured to appose sidewalls of a vessel to occlude the vesselin an expanded state, and a fluid injection port configured to injectradiopaque fluid into a vessel proximal to the expandable member in theexpanded state such that the radiopaque fluid pools proximate to theexpandable member and provides visualization of the vessel and branchvessels.

The expandable member may be coupled to the tubular body. The tubularbody may comprise the fluid injection port. The catheter system mayfurther comprise a second tubular body. The expandable member may becoupled to the second tubular body. The second tubular body may comprisethe fluid injection port. The targeting system may comprise anultrasound transducer. The targeting system may comprise anomnidirectional ultrasound transducer.

In some embodiments, a catheter system comprises, or alternativelyconsists essentially of, a tubular body, a targeting system coupled tothe tubular body, and an expandable member.

The expandable member may be coupled to the tubular body. The cathetersystem may further comprise a second tubular body. The expandable membermay be coupled to the second tubular body. The expandable member may beconfigured to appose sidewalls of a vessel to occlude the vessel. Thecatheter system may further comprise a fluid injection port. The tubularbody may comprise the fluid injection port. The catheter system mayfurther comprise a second tubular body comprising the fluid injectionport. The targeting system may comprise an ultrasound transducer. Thetargeting system may comprise an omnidirectional ultrasound transducer.

In some embodiments, a catheter system comprises, or alternativelyconsists essentially of, a tubular body, a targeting system coupled tothe tubular body, and a fluid injection port.

The tubular body may comprise the fluid injection port. The cathetersystem may further comprise a second tubular body comprising the fluidinjection port. The catheter system may further comprise an expandablemember. The expandable member may be coupled to the tubular body. Thecatheter system may further comprise a second tubular body. Theexpandable member may be coupled to the second tubular body. Theexpandable member may be configured to appose sidewalls of a vessel toocclude the vessel. The targeting system may comprise an ultrasoundtransducer. The targeting system may comprise an omnidirectionalultrasound transducer.

In some embodiments, a catheter system comprises, or alternativelyconsists essentially of, a tubular body, a fluid injection port, and anexpandable member.

The tubular body may comprise the fluid injection port. The cathetersystem may further comprise a second tubular body comprising the fluidinjection port. The expandable member may be coupled to the tubularbody. The catheter system may further comprise a second tubular body.The expandable member may be coupled to the second tubular body. Theexpandable member may be configured to appose sidewalls of a vessel toocclude the vessel. The catheter system may further comprise a targetingsystem. The targeting system may comprise an ultrasound transducer. Thetargeting system may comprise an omnidirectional ultrasound transducer.A method of identifying a bifurcation may comprise inserting thecatheter system into a first vessel, positioning the catheter system ata first location, expanding the expandable member to occlude the firstvessel, and delivering contrast material into the first vessel. Thecontrast material may pool proximate to the expandable member. Themethod may further comprise reviewing a shape of the contrast materialin the first vessel under fluoroscopy.

In some embodiments, a method of identifying a bifurcation comprises, oralternatively consists essentially of, inserting a catheter system intoa first vessel and positioning the catheter system at a first location.The catheter system comprises an expandable member and a fluid injectionport. The method further comprises expanding the expandable member toocclude the first vessel and delivering contrast material out of thefluid injection port. The contrast material pools proximate to theexpandable member. The method further comprises reviewing a shape of thecontrast material in the first vessel under fluoroscopy.

A single catheter may comprise the expandable member and the fluidinjection port. A first catheter may comprise the expandable member anda second catheter may comprise the fluid injection port. Expanding theexpandable member may comprise providing fluid flow through an inflationlumen in fluid communication with the expandable member. Expanding theexpandable member may comprise expanding the first vessel. The contrastmaterial may comprise at least one of iodine-based contrast and bariumsulfate-based contrast. Delivering the contrast material may compriseexpanding the first vessel. Reviewing the shape of the contrast materialmay comprise identifying the presence of at least one of a bifurcationand a branch vessel. The method may further comprise repositioning thecatheter system if at least one of the bifurcation and the branch vesselis present. The method may further comprise extending a needle fromanother catheter in a second vessel if at least one of the bifurcationand the branch vessel is not present. Extending the needle may compriseexiting the second vessel, traversing interstitial tissue between thesecond vessel and the first vessel, and entering the first vessel. Themethod may further comprise advancing a guidewire through the needle.The catheter system may comprise a capture element configured to guidethe guidewire into a guidewire lumen.

The catheter system may comprise a targeting system. Positioning thecatheter system at the first location may comprise targeting thetargeting system from a complementary targeting system on anothercatheter in a second vessel. The targeting system may comprise anultrasound receiver. The complementary targeting system may comprise anultrasound emitter. The ultrasound receiver may comprise anomnidirectional ultrasound transducer. The ultrasound emitter maycomprise a directional ultrasound transducer. The method may furthercomprise dilating the fistula.

The method may further comprise deploying a prosthesis at leastpartially in a fistula between the second vessel and the first vessel.After deploying the prosthesis, blood may be diverted from the firstvessel to the second vessel through the prosthesis. The method mayfurther comprise, after deploying the prosthesis, lining the firstvessel with a stent-graft including covering the collateral vessels ofthe first vessel. Lining the first vessel with the stent-graft maycomprise lining the first vessel with a plurality of stent grafts.Lining the first vessel with the plurality of stent-grafts may comprisefirst deploying a distal-most stent-graft of the plurality ofstent-grafts and last deploying a proximal-most stent-graft of theplurality of stent-grafts. After lining the first vessel with theplurality of stent-grafts, a proximal edge of a distal-most stent-graftof the plurality of stent-grafts may overlap a distal edge of a nextdistal-most stent-graft of the plurality of stent-grafts. After liningthe first vessel with the plurality of stent-grafts, a proximal edge ofa proximal-most stent-graft of the plurality of stent-grafts may overlapa distal edge of the prosthesis.

The method may further comprise making a valve in the first vesselincompetent. Making the valve in the first vessel incompetent may beafter lining the vessel with a stent-graft. Making the valve in firstthe vessel incompetent may comprise advancing a reverse valvulotomethrough the prosthesis and distally advancing the reverse valvulotome inthe first vessel to disable the valve. Making the valve in the firstvessel incompetent may comprise advancing a two-way valvulotomeproximate to the valve in a radially compressed state, radiallyexpanding the two-way valvulotome to a radially expanded state, and inthe radially expanded state, at least one of distally advancing thetwo-way valvulotome and proximally retracting the two-way valvulotome inthe first vessel to disable the valve. Radially expanding the two-wayvalvulotome may comprise at least one of proximally retracting a sheathand distally advancing the two-way valvulotome. A method of making avalve in a vessel incompetent may comprise advancing the two-wayvalvulotome proximate to the valve in the radially compressed state,radially expanding the two-way valvulotome to the radially expandedstate, and in the radially expanded state, at least one of distallyadvancing the two-way valvulotome and proximally retracting the two-wayvalvulotome in the vessel to disable the valve.

In some embodiments, a method of modifying a vessel including makingvalves in the vessel incompetent and covering collateral vessels of thevessel comprises, or alternatively consists essentially of, lining thevessel with a stent-graft including covering the collateral vessels ofthe vessel and after lining the vessel with the stent-graft, making avalve in the vessel incompetent.

The method may further comprise deploying a prosthesis at leastpartially in a fistula between a second vessel and the vessel. Afterdeploying the prosthesis, blood may be diverted from the second vesselto the vessel through the prosthesis. Lining the vessel with thestent-graft may be after deploying the prosthesis. The method mayfurther comprise dilating the fistula. The method may further compriseadvancing a needle from the second vessel to the vessel to form thefistula. Advancing the needle may comprise targeting a first catheter inthe vessel with a second catheter in the second vessel. The secondcatheter may comprise an ultrasound emitter. The first catheter maycomprise an ultrasound receiver. Targeting the catheter in the vesselwith the catheter in the second vessel may comprise targeting theultrasound receiver with the ultrasound emitter. The method may furthercomprise advancing a guidewire through the needle. A catheter system inthe vessel may comprise a capture element configured to guide theguidewire into a guidewire lumen. Lining the vessel with the stent-graftmay comprise lining the vessel with a plurality of stent grafts. Liningthe vessel with the plurality of stent-grafts may comprise firstdeploying a distal-most stent-graft of the plurality of stent-grafts andlast deploying a proximal-most stent-graft of the plurality ofstent-grafts. After lining the vessel with the plurality ofstent-grafts, a proximal edge of a distal-most stent-graft of theplurality of stent-grafts may overlap a distal edge of a nextdistal-most stent-graft of the plurality of stent-grafts. After liningthe vessel with the plurality of stent-grafts, a proximal edge of aproximal-most stent-graft of the plurality of stent-grafts may overlap adistal edge of a prosthesis in the fistula. Making the valve in thevessel incompetent may comprise distally advancing a reverse valvulotomein the vessel to disable the valve. Making the valve in the vesselincompetent may comprise advancing a two-way valvulotome proximate tothe valve in a radially compressed state, radially expanding the two-wayvalvulotome to a radially expanded state and in the radially expandedstate, at least one of distally advancing the two-way valvulotome andproximally retracting the two-way valvulotome in the vessel to disablethe valve. Radially expanding the two-way valvulotome may comprise atleast one of proximally retracting a sheath and distally advancing thetwo-way valvulotome. The method may further comprise promotingretroperfusion of blood into toes. Promoting retroperfusion of bloodinto toes may comprise inflating a first expandable member in a medialplantar vein to occlude the medial plantar vein. Promotingretroperfusion of blood into toes may comprise inflating a secondexpandable member in a lateral plantar vein to occlude the lateralplantar vein. Promoting retroperfusion of blood into toes may compriseincreasing hydrostatic pressure in a deep plantar venous arch.Increasing the hydrostatic pressure in the deep plantar venous arch maycomprise disabling venous valves and enabling reversal of blood flowinto metatarsal veins.

In some embodiments, a method of promoting retroperfusion of blood intotoes comprises, or alternatively consists essentially of, inflating afirst expandable member in a medial plantar vein to occlude the medialplantar vein and increasing hydrostatic pressure in a deep plantarvenous arch. Increasing the hydrostatic pressure in the deep plantarvenous arch may comprise disabling venous valves and enabling reversalof blood flow into metatarsal veins. The method may further compriseinflating a second expandable member in a lateral plantar vein toocclude the lateral plantar vein.

In some embodiments, a catheter system for promoting retroperfusion ofblood into toes comprises, or alternatively consists essentially of, afirst catheter comprising a first expandable member configured to beexpanded in a medial plantar vein to occlude the medial plantar vein anda second catheter comprising a second expandable member configured to beexpanded in a lateral plantar vein to occlude the lateral plantar vein.

The first catheter may be longitudinally movable through the secondcatheter and the second expandable member. The first catheter maycomprise an inflation lumen in fluid communication with the firstexpandable member. The second catheter may comprise an inflation lumenin fluid communication with the second expandable member. The firstcatheter may be configured to curve around a lateral plantar vein into amedial plantar vein.

In some embodiments, a two-way valvulotome comprises, or alternativelyconsists essentially of, a proximal portion, a distal portion, and anintermediate portion longitudinally between the proximal portion and thedistal portion. The intermediate portion comprises a distally facingblade and a proximally facing blade.

The intermediate portion may comprise a strut comprising the distallyfacing blade and the proximally facing blade. The intermediate portionmay comprise a plurality of struts. One strut of the plurality of strutsmay comprise the distally facing blade and the proximally facing blade.Each strut of the plurality of struts may comprise a distally facingblade and a proximally facing blade. At least one strut of the pluralityof struts may comprise a distally facing blade. At least one strut ofthe plurality of struts may comprise a proximally facing blade. Theintermediate portion may comprise three struts. The three struts may beevenly circumferentially spaced. The intermediate portion may beradially expandable. The intermediate portion may be self-expanding uponrelease from a sheath. The proximal portion may be coupled to a pusherelement. The intermediate portion may be laser cut (e.g., from ahypotube or a sheet). At least one of the distally facing blade and theproximally facing blade may be rotated relative to a circumference ofthe intermediate portion.

In some embodiments, a method of making a valve in a vessel incompetentcomprises, or alternatively consists essentially of, advancing a two-wayvalvulotome proximate to the valve in a radially compressed state,radially expanding the two-way valvulotome to a radially expanded state,and in the radially expanded state, at least one of distally advancingthe two-way valvulotome and proximally retracting the two-wayvalvulotome in the vessel to disable the valve.

Advancing the two-way valvulotome proximate to the valve may compriseadvancing the two-way valvulotome in a direction opposite native fluidflow. Advancing the two-way valvulotome proximate to the valve maycomprise advancing the two-way valvulotome in a direction of nativefluid flow. Advancing the two-way valvulotome proximate to the valve maycomprise advancing the two-way valvulotome proximal to the valve.Advancing the two-way valvulotome proximate to the valve may compriseadvancing the two-way valvulotome distal to the valve.

In some embodiments, a catheter for capturing a guidewire comprises, oralternatively consists essentially of, a catheter body, a captureelement, and a guidewire lumen in communication with the captureelement.

The capture element may be configured to deploy from a distal end of thecatheter body. The capture element may be configured to deploy from aside of the catheter body. The capture element may have a collapsedstate and an expanded state. The capture element may comprise shapememory material configured to change to the expanded state at bodytemperature. The capture element may have an angle between 110° and 150°in the expanded state. The guidewire lumen may comprise an expandedportion proximate to the capture element. The catheter may furthercomprise an expandable element configured to expand the capture element.The expandable element may comprise an inflatable member. The catheterbody may comprise an inflation lumen in fluid communication with theinflatable member. The expandable element may be movable relative to thecatheter body.

In some embodiments, a method of making valves incompetent comprises, oralternatively consists essentially of, forming a fistula between a firstvessel and a second vessel. The first vessel may be an artery. Thesecond vessel may be a vein. Forming the fistula comprises inserting afirst catheter into the first vessel. The first catheter comprises anultrasound emitting transducer and a needle configured to radiallyextend from the first catheter. Forming the fistula further comprisesinserting a second catheter into the second vessel. The second cathetercomprises an ultrasound receiving transducer. Forming the fistulafurther comprises emitting an ultrasound signal from the ultrasoundemitting transducer and after the ultrasound signal is received by theultrasound receiving transducer, extending the needle from the firstcatheter. Extending the needle comprises exiting the first vessel,traversing interstitial tissue between the first vessel and the secondvessel, and entering the second vessel. The method further comprisesdeploying a prosthesis at least partially in the fistula. Afterdeploying the implantable prosthesis, blood is diverted from the firstvessel to the second vessel through the prosthesis. The method furthercomprises making valves in the second vessel incompetent. Making thevalves in the second vessel incompetent comprises using a reversevalvulotome to cut the valves and lining the second vessel with a stent.

The stent may comprise a covering or a graft. Lining the second vesselmay comprise covering collateral vessels of the second vessel. The stentmay be separate from the prosthesis. The stent may be spaced from theprosthesis along a length of the second vessel. The stent may beintegral with the prosthesis.

In some embodiments, a method of making valves incompetent comprises, oralternatively consists essentially of, forming a fistula between a firstvessel and a second vessel. Forming the fistula comprises inserting acatheter into the first vessel. The catheter comprises a needleconfigured to radially extend from the first catheter. Forming thefistula further comprises extending the needle from the first catheter.Extending the needle comprises exiting the first vessel, traversinginterstitial tissue between the first vessel and the second vessel, andentering the second vessel. The method further comprises deploying aprosthesis at least partially in a fistula between a first vessel and asecond vessel. After deploying the implantable prosthesis, blood isdiverted from the first vessel to the second vessel through theprosthesis. The method further comprises making valves in the secondvessel incompetent. Making the valves in the second vessel incompetentcomprises at least one of using a reverse valvulotome to cut the valves,inflating a balloon, expanding a temporary stent, and lining the secondvessel with an implantable stent.

The implantable stent may comprise a covering or a graft. Lining thesecond vessel may comprise covering collateral vessels of the secondvessel. The implantable stent may be separate from the prosthesis. Theimplantable stent may be integral with the prosthesis. The firstcatheter may comprise an ultrasound emitting transducer. Forming thefistula may comprise inserting a second catheter into the second vessel,the second catheter comprising an ultrasound receiving transducer,emitting an ultrasound signal from the ultrasound emitting transducer,and extending the needle from the first catheter after the ultrasoundsignal is received by the ultrasound receiving transducer.

In some embodiments, a method of making valves incompetent comprises, oralternatively consists essentially of, deploying a prosthesis at leastpartially in a fistula between a first vessel and a second vessel. Afterdeploying the implantable prosthesis, blood is diverted from the firstvessel to the second vessel through the prosthesis. The method furthercomprises making valves in the second vessel incompetent.

Making the valves in the second vessel incompetent may comprise using areverse valvulotome to cut the valves. Making the valves in the secondvessel incompetent may comprise lining the second vessel with a stent.The stent may comprise a covering or a graft. Lining the second vesselmay comprise covering collateral vessels of the second vessel. The stentmay be separate from the prosthesis. The stent may be spaced from theprosthesis along a length of the second vessel. A proximal segment ofthe stent may longitudinally overlap a distal segment of the prosthesis.The stent may be integral with the prosthesis. Making the valves in thesecond vessel incompetent may comprise using a reverse valvulotome tocut the valves and lining the second vessel with a stent. Making thevalves in the second vessel incompetent may comprise at least one ofinflating a balloon and expanding a temporary stent. Making the valvesin the second vessel incompetent may comprise inflating a balloon.Making the valves in the second vessel incompetent may compriseexpanding a temporary stent.

In some embodiments, an implantable prosthesis for treating an occlusionin a first vessel comprises, or alternatively consists essentially of, aplurality of filaments woven together into a woven structure, a proximalend, a distal end, sidewalls between the proximal end and the distalend, a lumen defined by the sidewalls, and a porosity sufficient todirect fluid flow through the lumen substantially without perfusingthrough the sidewalls.

The porosity may be between about 0% and about 50%. The porosity may bebetween about 5% and about 50%. The prosthesis may be substantially freeof graft material. The prosthesis may comprise a first longitudinalsegment having the porosity and a second longitudinal segment having asecond porosity different than the porosity. The second longitudinalsegment may have a parameter different than the first longitudinalsegment. The parameter may comprise at least one of braid angle,filament diameter, filament material, woven structure diameter, wovenstructure shape, and supplemental support structure. The prosthesis mayfurther comprise a third longitudinal segment between the firstlongitudinal segment and the second longitudinal segment. The thirdlongitudinal segment may have a parameter different than at least one ofthe first longitudinal segment and the second longitudinal segment. Theparameter may comprise at least one of braid angle, filament diameter,filament material, woven structure diameter, woven structure shape, andsupplemental support structure. The prosthesis may further comprise asupplemental support structure. The supplemental support structure maycomprise a second plurality of filaments woven together into a secondwoven structure, the second plurality of filaments having a parameterdifferent than the plurality of filaments. The parameter may comprise atleast one of braid angle, filament diameter, woven structure diameter,and filament material. The supplemental support structure may comprise acut hypotube. The plurality of filaments may comprise a filamentcomprising a shape memory material (e.g., nitinol) and a prosthesiscomprising a biocompatible polymer (e.g., Dacron®, Kevlar®).

In some embodiments, an implantable prosthesis for treating an occlusionin a first vessel comprises, or alternatively consists essentially of, aproximal end, a distal end, sidewalls between the proximal end and thedistal end, a lumen defined by the sidewalls, a first longitudinalsection configured to anchor in a first cavity, a second longitudinalsection configured to anchor in a second cavity, and a thirdlongitudinal section between the first longitudinal section and thesecond longitudinal section. At least one of the first longitudinalsection and the third longitudinal section comprises a porositysufficient to direct fluid flow through the lumen substantially withoutperfusing through the sidewalls.

The porosity may be between about 0% and about 50%. The porosity may bebetween about 5% and about 50%. The prosthesis may be substantially freeof graft material. The second longitudinal segment may have a parameterdifferent than the first longitudinal segment. The parameter maycomprise at least one of braid angle, filament diameter, filamentmaterial, diameter, shape, and supplemental support structure. The thirdlongitudinal segment may comprise a second porosity different than theporosity. The first longitudinal segment may be balloon expandable. Thesecond longitudinal segment may be self expanding. The prosthesis maycomprise a plurality of filaments woven together into a woven structure.The plurality filaments may comprise a filament comprising a shapememory material (e.g., nitinol) and a prosthesis comprising abiocompatible polymer (e.g., Dacron®, Kevlar®). The third longitudinalsection may have a parameter different than at least one of the firstlongitudinal section and the second longitudinal section. The parametermay comprise at least one of braid angle, filament diameter, filamentmaterial, diameter, shape, and supplemental support structure. Theprosthesis may further comprise a supplemental support structure. Thefirst longitudinal section may be substantially cylindrical and may havea first diameter, the second longitudinal section may be substantiallycylindrical and may have a second diameter larger than the firstdiameter, and the third longitudinal section may be frustoconical andmay taper from the first diameter to the second diameter. The firstlongitudinal section may be substantially cylindrical and may have afirst diameter and the second longitudinal section and the thirdlongitudinal section may be frustoconical and taper from the firstdiameter to a second diameter larger than the first diameter.

In some embodiments, an implantable prosthesis for treating an occlusionin a first vessel comprises a plurality of filaments woven together intoa woven structure, a proximal end, a distal end, sidewalls between theproximal end and the distal end, a lumen defined by the sidewalls, and aporosity between about 5% and about 50%.

The porosity may be configured to direct fluid flow substantiallythrough the lumen. The prosthesis may comprise a first longitudinalsegment having the porosity and a second longitudinal segment having asecond porosity different than the porosity.

In some embodiments, a kit comprises the prosthesis and a fistulaformation system. The kit may further comprise a valve disabling device.In some embodiments, a kit comprises the prosthesis and a valvedisabling device. The kit may comprising a prosthesis delivery systemincluding the prosthesis. In some embodiments, a method comprisesdeploying the prosthesis in a fistula between the first vessel and asecond vessel. The valve disabling device may comprise a reversevalvulotome. The valve disabling device may comprise a balloon. Thevalve disabling device may comprise a venous stent. The venous stent maycomprise a covering or graft. The venous stent may be integral with theprosthesis.

In some embodiments, a method of diverting fluid flow from a firstvessel to a second vessel in which the first vessel comprises anocclusion comprises deploying a prosthesis at least partially in afistula between the first vessel and the second vessel. The prosthesiscomprises a plurality of filaments woven together into a woven structurecomprising a porosity less than about 50%. After deploying theimplantable prosthesis, blood may be diverted from the first vessel tothe second vessel through the prosthesis.

The first vessel may be an artery. The vessel passage may be a vein. Themethod may comprise dilating the fistula. The first vessel may besubstantially parallel to the second vessel. Deploying the prosthesismay comprise allowing the prosthesis to self-expand. Deploying theprosthesis may comprise balloon expanding the prosthesis. Deploying theprosthesis may comprise deploying the woven structure and deploying asupplemental support structure. Deploying the supplemental supportstructure may be before deploying the woven structure. Deploying thesupplemental support structure may be after deploying the wovenstructure. The supplemental support structure may comprise a secondplurality of filaments woven into a second woven structure. Thesupplemental support structure may comprise cut hypotube. The method mayfurther comprise forming the fistula. Forming the fistula may compriseinserting a launching catheter into the first vessel and inserting atarget catheter into the second vessel. The launching catheter maycomprise an ultrasound emitting transducer and a needle configured toradially extend from the launching catheter. The target catheter maycomprise an ultrasound receiving transducer. Forming the fistula maycomprise emitting an ultrasound signal from the ultrasound emittingtransducer, during emitting the ultrasound signal and until theultrasound signal may be received by the ultrasound receivingtransducer, at least one of rotating the launching catheter andlongitudinally moving the launching catheter, and after the ultrasoundsignal is received by the ultrasound receiving transducer, extending theneedle from the launching catheter, wherein extending the needlecomprises exiting the first vessel, traversing interstitial tissuebetween the first vessel and the second vessel, and entering the secondvessel. The method may further comprise making valves in the secondvessel incompetent. Making valves in the second vessel incompetent maycomprise using a reverse valvulotome to cut the valves. Making valves inthe second vessel incompetent may comprise inflating a balloon. Makingvalves in the second vessel incompetent may comprise expanding a stent.Making valves in the second vessel incompetent may comprise lining thesecond vessel with a stent. The stent may comprise a covering or agraft. Lining the second vessel may comprise covering collateral vesselsof the second vessel. The stent may be separate from the prosthesis. Thestent may be spaced from the prosthesis along a length of the secondvessel. An end of the stent may abut an end of the prosthesis. A portionof the stent may longitudinally overlap a portion of the prosthesis. Theportion of the stent may be radially inward of the portion of theprosthesis. The method may comprise expanding the stent after deployingthe prosthesis. The portion of the prosthesis may be radially inward ofthe portion of the stent. The method may comprise expanding the stentbefore deploying the prosthesis. The stent may be integral with theprosthesis.

In some embodiments, an implantable prosthesis for maintaining patencyof an anastomosis between an artery and a vein in a lower extremitycomprises a first section configured to reside in a lower extremityartery, a second section configured to reside in a lower extremity vein,and a third section longitudinally between the first section and thesecond section. The third section is configured to maintain patency ofan anastomosis between the artery and the vein.

The first section may be configured to appose the walls of the lowerextremity artery. The first section may comprise barbs. The secondsection may be configured to appose the walls of the lower extremityvein. The second section may comprise barbs. At least one of the firstsection, the second section, and the third section may beself-expanding. At least one of the first section, the second section,and the third section may be balloon expandable. A length of the secondsection may be greater than a length of the first section. The secondsection may be configured to disable valves the lower extremity vein.The second section may be configured to cover collateral vessels of thelower extremity vein.

In some embodiments, a method of diverting fluid flow from a firstvessel to a second vessel in a lower extremity comprises forming anaperture between the first vessel and the second vessel, and expandingthe aperture to form an anastomosis.

Forming the aperture may comprise forcing a wire from the first bloodvessel into the second blood vessel. Forming the aperture may comprisetraversing a needle from the first blood vessel into the second bloodvessel. Expanding the aperture may comprise dilating the aperture usingat least one balloon. Dilating the aperture may comprise using aplurality of balloons having progressively higher diameters. A firstballoon of the plurality of balloons may have a diameter of about 1.5 mmand wherein a last balloon of the plurality of balloons may have adiameter of about 3 mm. The plurality of balloons may comprise a firstballoon having a diameter of about 1.5 mm, a second balloon having adiameter of about 2.0 mm, a third balloon having a diameter of about 2.5mm, and a third balloon having a diameter of about 3.0 mm. Dilating theaperture using the plurality of balloons may comprise usingprogressively higher balloon inflation pressures. The method may notinclude (e.g., be devoid of or free from) placing a prosthesis (e.g.,without use of a stent, graft, scaffolding, or other prosthesis).Positions of the first vessel and the second vessel may be substantiallymaintained by anatomy surrounding the first vessel and the secondvessel. The method may further comprise placing a prosthesis in theanastomosis. Placing the prosthesis in the anastomosis may compriseanchoring the prosthesis in at least one of the first vessel and thesecond vessel. The first vessel may comprise a lateral plantar artery.The second vessel may comprise a lateral plantar vein.

In some embodiments, a catheter for capturing a guidewire comprises, oralternatively consists essentially of, a sheath and an expandableelement. The expandable element has a collapsed state when in the sheathand an expanded state when out of the sheath. The expandable elementcomprises a plurality of cells configured to snare a guidewire.

The catheter may further comprise a guidewire sheath extending throughthe sheath and the expandable element. A proximal end of the expandableelement may be coupled to the guidewire sheath. The expandable elementmay be configured to expand a vessel upon deployment. The expandableelement may be visible under fluoroscopy. The expandable element maycomprise struts defining the plurality of cells. The struts may bedeflectable if contacted by a needle. The catheter may further comprisean ultrasound receiving transducer. The ultrasound receiving transducermay be distal to the expandable element. The ultrasound receivingtransducer may be longitudinally between a proximal end of theexpandable element and a distal end of the expandable element. Theultrasound receiving transducer may be proximal to the expandableelement. A method of capturing a guidewire may comprise inserting thecatheter into a first vessel, expanding the expandable element to theexpanded state in the first vessel, and extending a needle from a secondvessel, through interstitial tissue, and into the first vessel betweenthe proximal end of the expandable element and the distal end of theexpandable element. Extending the needle may comprise extending througha cell of the plurality of cells. The method may further compriseextending a guidewire through the needle and into the expandable elementand collapsing the expandable element towards the collapsed state.Collapsing the expandable element may comprise snaring the guidewire.

In some embodiments, a method of capturing a guidewire comprises, oralternatively consists essentially of, expanding an expandable elementto an expanded state in a first vessel, and extending a needle from asecond vessel, through interstitial tissue, and into the first vesselbetween a proximal end of the expandable element and a distal end of theexpandable element. The expandable element comprises a plurality ofcells. Extending the needle comprises extending through a cell of theplurality of cells. The method further comprises extending a guidewirethrough the needle and into the expandable element and collapsing theexpandable element towards a collapsed state. Collapsing the expandableelement comprises snaring the guidewire.

Collapsing the expandable element may comprise twisting the expandableelement. Expanding the expandable element may comprise expanding thefirst vessel. Extending the needle may comprise targeting the expandableelement under fluoroscopy. The method may further comprise proximallyretracting the expandable element. Proximally retracting the expandableelement may comprise routing the guidewire through the first vessel.

In some embodiments, a device for deploying a tubular structurecomprises, or alternatively consists essentially of, a handle body, aknob, and a slider. The handle body comprises a first segment comprisingthreads, a second segment longitudinally adjacent and proximal to thefirst segment, and a longitudinal slot. The second segment is free ofthreads. The knob comprises threads. The knob is at a distal end of thefirst segment in a starting position. The slider is operably connectedto the knob. The slider is coupled to a sheath. The knob is configuredto rotate proximally about the handle body for the first segment and isconfigured to proximally slide along the handle body for the secondsegment. The slider is configured to proximally retract the sheath afirst amount during rotating the knob and is configured to proximallyretract the sheath a second amount during sliding the knob. The deviceis configured to fully deploy the tubular structure after the sheath isretracted the second amount.

The first amount may be less than the second amount. The first amountmay be between 10% and 50% of the second amount. The tubular structuremay comprise a stent. The tubular structure may comprise a stent-graft.

In some embodiments, a method of deploying a tubular structurecomprises, or alternatively consists essentially of, rotating a knobabout a handle body. Rotating the knob about the handle body comprisesproximally retracting a sheath and deploying a first amount of thetubular structure. The method further comprises, after rotating the knobabout the handle body, proximally sliding the knob along the handlebody. Proximally sliding the knob along the handle body comprisesproximally retracting the sheath deploying a second amount of thetubular structure. The first amount and the second amount are the fullamount of the tubular structure.

The first amount may be less than the second amount. The first amountmay be between 10% and 50% of the second amount. The tubular structuremay comprise a stent. The tubular structure may comprise a stent-graft.

In some embodiments, a device for deploying a tubular structurecomprises, or alternatively consists essentially of, a sheath, a handlebody, a knob comprising a worm gear comprising teeth, and a slidercoupled to the sheath. The slider comprises a first portion in thehandle body, a second portion outside the handle body; and a worm screwcomprising teeth configured to interact with the teeth of the worm gear.The slider is configured to proximally retract the sheath a first amountduring rotating the knob and is configured to proximally retract thesheath a second amount during sliding the slider. The device isconfigured to fully deploy the tubular structure after the sheath isretracted the second amount.

The first amount may be less than the second amount. The first amountmay be between 10% and 50% of the second amount. The tubular structuremay comprise a stent. The tubular structure may comprise a stent-graft.The handle body may comprise a longitudinal slot. The slider maycomprise a third portion extending through the longitudinal slot. Thehandle body may comprise a second longitudinal slot. The slider maycomprise a fourth portion outside the handle body and a fifth portionextending through the second longitudinal slot. The fourth portion maybe on an opposite side of the handle body than the second portion. Thehandle body may comprise a shell at least partially covering the secondportion of the slider until the sheath may be proximally retracted thefirst amount.

In some embodiments, a method of deploying a tubular structurecomprises, or alternatively consists essentially of, rotating a knob.Rotating the knob comprises proximally retracting a sheath and deployinga first amount of the tubular structure. The method further comprises,after rotating the knob, proximally sliding a slider along a handlebody. Proximally sliding the slider along the handle body comprisesproximally retracting the sheath a second distance and deploying asecond amount of the tubular structure. The first amount and the secondamount are the full amount of the tubular structure.

The first amount may be less than the second amount. The first amountmay be between 10% and 50% of the second amount. The tubular structuremay comprise a stent. The tubular structure may comprise a stent-graft.The knob may comprise a worm gear comprising teeth. The slider maycomprise a worm screw comprising teeth configured to interact with theteeth of the worm gear. The handle body may comprise a longitudinalslot. The slider may comprise a first portion in the handle body, asecond portion outside the handle body, and a third portion extendingthrough the longitudinal slot. The handle body may comprise a secondlongitudinal slot. The slider may comprise a fourth portion outside thehandle body and a fifth portion extending through the secondlongitudinal slot. The fourth portion may be on an opposite side of thehandle body than the second portion. Proximally retracting the slidermay comprise gripping the second portion and the fourth portion. Thehandle body may comprise a shell at least partially covering the secondportion of the slider until the sheath may be proximally retracted thefirst amount. An axis of rotation of the knob may be transverse to alongitudinal axis of the handle body.

In some embodiments, a method of accessing a tibial vein of a subjectcomprises, or alternatively consists essentially of, positioning a firsttourniquet above a knee of a leg, positioning a second tourniquet abovean ankle of the leg, injecting a quantity of contrast through ametatarsal vein, and using fluoroscopy to prepare a venogram to imageveins of a foot of the leg.

The first tourniquet may be a different type than the second tourniquet.The first tourniquet may be a same type as the second tourniquet. Thefirst tourniquet may be a same size as the second tourniquet. The firsttourniquet may be a different size than the second tourniquet. Themethod may further comprise positioning the subject in a reverseTrendelenburg position. The method may further comprise, after injectingthe quantity of contrast through the metatarsal vein, flattening thesubject. The contrast may comprise non-ionic contrast. The contrast maycomprise a mixture of contrast material and saline. The contrast maycomprise a 50/50 dilution of the contrast material and the saline. Thequantity of contrast may comprise between 5 mL and 50 mL. The metatarsalvein may be a dorsal metatarsal vein. The metatarsal vein may be aplantar metatarsal vein. The method may further comprise palpating themetatarsal vein. The method may further comprise selecting the tibialvein using the venogram. The method may further comprise advancing aguidewire to the target tibial vein. The method may further compriseremoving the second tourniquet. The method may further comprise trackinga functional catheter over the guidewire. The functional catheter maycomprise a catheter for forming a fistula (e.g., a target catheter, alaunching catheter). The functional catheter may comprise snare.

In some embodiments, a method of accessing a lateral plantar vein of asubject comprises, or alternatively consists essentially of, positioninga first tourniquet above an ankle of a leg, placing a needle in a dorsalmedial marginal vein towards toes of a foot of the leg, advancing afirst guidewire into a first metatarsal vein of the foot, injecting aquantity of contrast, and using fluoroscopy to prepare a venogram toimage veins of a foot of the leg.

The contrast may comprise non-ionic contrast. The contrast may comprisea mixture of contrast material and saline. The contrast may comprise a50/50 dilution of the contrast material and the saline. The quantity ofcontrast may comprise between 5 mL and 50 mL. The method may furthercomprise selecting a larger to two lateral plantar veins using thevenogram. The method may further comprise advancing the first guidewireto at least one of a crossing point or above the ankle and usingultrasound to survey veins on a bottom of the foot to view a position ofthe first guidewire. The method may further comprise advancing the firstguidewire to at least one of a crossing point or above the ankle, usingultrasound to survey veins on a bottom of the foot to view a position ofthe first guidewire, and accessing a lateral plantar vein containing thefirst guidewire of the foot as distal as possible in a plantar arch ofthe foot at a second access site. The method may further compriseadvancing a second guidewire into the lateral plantar vein. The methodmay further comprise advancing the second guidewire into a posteriortibial vein and up to a crossing point. The method may further compriseremoving the first guidewire. The method may further comprise removingthe tourniquet. The method may further comprise tracking a functionalcatheter over the guidewire. The functional catheter may comprise acatheter for forming a fistula (e.g., a target catheter, a launchingcatheter). The functional catheter may comprise snare.

In some embodiments, a method of performing an ascending venogramprocedure comprises, or alternatively consists essentially of, injectinga quantity of contrast into venous vasculature from a first metatarsalvein.

In some embodiments, a method of performing a descending venogramprocedure comprises, or alternatively consists essentially of, injectinga quantity of contrast into venous vasculature from a great saphenousvein towards a foot.

In some embodiments, a method of aligning a catheter for a venousarterialization procedure comprises inserting a first catheter in afirst vessel. The first catheter comprises a needle aperture on a firstside of the needle, a radiopaque marker being distal to the needleaperture and being on a second side of the first catheter opposite thefirst side, and a needle configured to extend through the needleaperture. The radiopaque marker is visible under fluoroscopy. The methodfurther comprises inserting a second catheter in a second vessel. Thesecond catheter comprises a balloon. The method further comprisesexpanding the balloon. Expanding the balloon comprises inflating theballoon with radiopaque material visible under fluoroscopy. The methodfurther comprises longitudinally advancing the first catheter until theradiopaque marker is proximate the second catheter in the second vessel,and aligning the needle aperture of the first catheter with the secondcatheter. Aligning the needle aperture comprising rotating the firstcatheter in the first vessel such that the radiopaque marker transitionsbetween a first position and a second position. The method furthercomprises monitoring rotation of the radiopaque marker towards thesecond position to confirm rotational alignment of the needle aperturewith the second catheter, and after confirming rotational alignment,extending the needle out of the needle aperture of the first catheter.Extending the needle comprises exiting the first vessel, traversinginterstitial tissue between the first vessel and the second vessel, andentering the second vessel.

The method may further comprise extending a guidewire through the needleand into the second vessel, and entangling the guidewire in the secondcatheter in the second vessel. Entangling the guidewire may compriseclosing an expandable member of the second catheter. The method mayfurther comprise, after extending the guidewire, moving the secondcatheter to detect corresponding movement of the guidewire to confirmentanglement of the guidewire in the second catheter. The method mayfurther comprise moving the second catheter to move the guidewirethrough the second vessel. Moving the second catheter to move theguidewire through the second vessel may comprise exiting the secondvessel at a location in a foot.

In some embodiments, a method of aligning a catheter for a venousarterialization procedure comprises inserting a first catheter in afirst vessel. The first catheter comprises a radiopaque marker, and aneedle extendable along an extension path. The method further comprisesinserting a second catheter in a second vessel. The second cathetercomprises an expandable member. The expandable member comprises aradiopaque material visible under fluoroscopy. The method furthercomprises expanding the expandable member, and aligning the needle ofthe first catheter with the second catheter. Aligning the needlecomprises rotating the first catheter in the first vessel such that theradiopaque marker transitions between a first position and a secondposition. The method further comprises monitoring the rotation of theradiopaque marker towards the second position to confirm rotationalalignment of the needle extension path with the second catheter, andafter confirming rotational alignment, extending the needle out of thefirst catheter and along the extension path. Extending the needlecomprises exiting the first vessel, traversing interstitial tissuebetween the first vessel and the second vessel, and entering the secondvessel.

The method may further comprise extending a guidewire through the needleand into the second vessel. Extending the guidewire may compriseentangling the guidewire in the expandable member of the secondcatheter. The method may further comprise retracting the expandablemember through the second vessel. Retracting the expandable member maycomprise advancing the guidewire through the second vessel. Entanglingthe guidewire may comprise closing an expandable member of the secondcatheter. The radiopaque marker may be on a side of the first catheteropposite the needle extension path. The radiopaque marker may be distalto a needle exit aperture. The second catheter may comprise a balloon.The balloon may be inflated with the radiopaque material.

In some embodiments, a method of aligning a catheter for a venousarterialization procedure comprises inserting a first catheter in afirst vessel. The first catheter comprises a radiopaque marker, and aneedle. The method further comprises inserting a second catheter in asecond vessel. The second catheter comprises an expandable member. Themethod further comprises expanding the expandable member. The expandedexpandable member comprises radiopaque material. The method furthercomprises aligning an extension path of the needle with the secondvessel using the radiopaque marker and the radiopaque material, andextending the needle out of the first vessel, through interstitialtissue between the first vessel and the second vessel, and into thesecond vessel.

The method may further comprise extending a guidewire through the needleand into the second vessel, and entangling the guidewire in the secondcatheter. Entangling the guidewire may comprise closing the expandablemember. The method may further comprise moving the second catheter tomove the guidewire through the second vessel. Aligning the extensionpath of the needle with the second vessel may comprise rotating thefirst catheter in the first vessel such that the radiopaque markertransitions between a first position and a second position. The firstposition may comprise a first thickness visible under fluoroscopy. Thesecond position may comprise a second thickness visible underfluoroscopy. The first thickness may be different than the secondthickness. The first catheter may comprise a needle aperture on a firstside. The radiopaque marker may be on a second side of the firstcatheter opposite the first side. The first catheter may comprise aneedle aperture proximal to the radiopaque marker. The expandable membermay comprise a balloon. Expanding the expandable member may compriseinflating the balloon with the radiopaque material.

In some embodiments, a method of accessing a tibial vein of a subjectcomprises positioning the subject in a reverse Trendelenburg position,positioning a first tourniquet above a knee of a leg, positioning asecond tourniquet above an ankle of the leg, injecting a quantity ofcontrast through a metatarsal vein, after injecting the quantity ofcontrast through the metatarsal vein, flattening the subject, usingfluoroscopy to prepare a venogram to image veins of a foot of the leg,selecting the tibial vein using the venogram, advancing a guidewire tothe selected tibial vein, removing the second tourniquet, tracking afunctional catheter over the guidewire, snaring a second guidewireextending from an artery using the functional catheter, retracting thesecond guidewire out of the foot, and tracking a second functionalcatheter over the second guidewire. The metatarsal vein may be a dorsalmetatarsal vein. The metatarsal vein may be a plantar metatarsal vein.The functional catheter may comprise a catheter for forming a fistula(e.g., a target catheter, a launching catheter). The second functionalcatheter may comprise a valve disabling device. The valve disablingdevice may comprise a valvulotome. The valve disabling device maycomprise a cutting balloon. The valve disabling device may comprise anatherectomy device.

In some embodiments, a method of accessing a tibial vein of a subjectcomprises injecting a quantity of contrast through a metatarsal vein,using fluoroscopy to prepare a venogram to image veins of a foot of theleg, selecting the tibial vein using the venogram, advancing a guidewireto the selected tibial vein, tracking a functional catheter over theguidewire, extending a second guidewire from an artery into the tibialvein, snaring the second guidewire using the functional catheter,retracting the second guidewire out of the foot, and tracking a secondfunctional catheter over the second guidewire.

The metatarsal vein may be a dorsal metatarsal vein. The metatarsal veinmay be a plantar metatarsal vein. The functional catheter may comprise acatheter for forming a fistula (e.g., a target catheter, a launchingcatheter). The second functional catheter may comprise a valve disablingdevice. The valve disabling device may comprise a valvulotome. The valvedisabling device may comprise a cutting balloon. The valve disablingdevice may comprise an atherectomy device.

In some embodiments, a method of accessing a tibial vein of a subjectcomprises injecting a quantity of contrast through a metatarsal vein,using fluoroscopy to prepare a venogram to image veins of a foot of theleg, selecting the tibial vein using the venogram, advancing a guidewireto the selected tibial vein, and tracking a functional catheter over theguidewire.

The metatarsal vein may be a dorsal metatarsal vein. The metatarsal veinmay be a plantar metatarsal vein. The functional catheter may comprisean element configured to snare a guidewire. The method may furthercomprise snaring a second guidewire extending from an artery using thefunctional catheter, and retracting the second guidewire. The method mayfurther comprise tracking a second functional catheter over the secondguidewire. The functional catheter may comprise a catheter for forming afistula (e.g., a target catheter, a launching catheter). The secondfunctional catheter may comprise a valve disabling device. The valvedisabling device may comprise a valvulotome. The valve disabling devicemay comprise a cutting balloon. The valve disabling device may comprisean atherectomy device.

In some embodiments, a cutting snare system comprises or consistsessentially of a snaring structure, and a valvulotome structure.

The system may further comprise an outer sheath. The snaring structureand the valvulotome structure may be exchangeable in the outer sheath.The valvulotome structure may be proximal to the snaring structure. Thesnaring structure may be configured to extend from a distal end of theouter sheath. The valvulotome structure may be monolithic with thesnaring structure. The outer sheath may comprise a plurality ofapertures. The valvulotome structure may be configured to extend fromthe outer sheath laterally through the plurality of apertures. Thesnaring structure may comprise a plurality of cells configured toreceive a guidewire. The snaring structure may comprise a plurality ofstruts configured to snare a guidewire. The snaring structure maycomprise a plurality of wires configured to snare a guidewire. Thevalvulotome structure may be proximal to the snaring structure. Thevalvulotome structure may be distal to the snaring structure. Thevalvulotome structure may be monolithic with the snaring structure. Thesnaring structure may have a first diameter and the valvulotomestructure may have a second diameter smaller than the first diameter.The snaring structure may be configured to evert into the valvulotomestructure upon application of a longitudinal force to the snaringstructure. The valvulotome structure may be separate from the snaringstructure. The valvulotome structure may be configured to telescope inthe snaring structure. The snaring structure may be configured totelescope in the valvulotome structure. The valvulotome structure maycomprise an expandable member configured to apply radially outward forceto the snaring structure. The valvulotome structure may comprise aplurality of blades. The plurality of blades may comprise between twoblades and eight blades. The plurality of blades may comprise threeblades. The plurality of blades may comprise four blades. The pluralityof blades may face proximally. The plurality of blades may facedistally. The plurality of blades may face proximally and distally.

In some embodiments, a cutting snare system comprises or consistsessentially of a snaring structure comprising a plurality of cellsconfigured to receive a guidewire, a valvulotome structure comprisingbetween two proximally facing blades and eight proximally facing blades,and an outer sheath. The snaring structure and the valvulotome structureare expandable from the outer sheath. The valvulotome structure may bemonolithic with the snaring structure.

In some embodiments, a method of accessing a plantar vein of a subjectcomprises positioning the subject in a reverse Trendelenburg position,positioning a first tourniquet above a knee of a leg, positioning asecond tourniquet above an ankle of the leg, injecting a quantity ofcontrast through a metatarsal vein, after injecting the quantity ofcontrast through the metatarsal vein, flattening the subject, usingfluoroscopy to prepare a venogram to image veins of a foot of the leg,selecting the plantar vein using the venogram, advancing a guidewire tothe selected plantar vein, removing the second tourniquet, tracking afunctional catheter over the guidewire, snaring a second guidewireextending from an artery using the functional catheter, retracting thesecond guidewire out of the foot, and tracking a second functionalcatheter over the second guidewire.

The metatarsal vein may be a dorsal metatarsal vein. The metatarsal veinmay be a plantar metatarsal vein. The functional catheter may comprise acatheter for forming a fistula (e.g., a target catheter, a launchingcatheter). The second functional catheter may comprise a valve disablingdevice. The valve disabling device may comprise a valvulotome. The valvedisabling device may comprise a cutting balloon. The valve disablingdevice may comprise an atherectomy device.

In some embodiments, a method of accessing a plantar vein of a subjectcomprises injecting a quantity of contrast through a metatarsal vein,using fluoroscopy to prepare a venogram to image veins of a foot of theleg, selecting the plantar vein using the venogram, advancing aguidewire to the selected plantar vein, tracking a functional catheterover the guidewire, extending a second guidewire from an artery into theplantar vein, snaring the second guidewire using the functionalcatheter, retracting the second guidewire out of the foot, and trackinga second functional catheter over the second guidewire.

The metatarsal vein may be a dorsal metatarsal vein. The metatarsal veinmay be a plantar metatarsal vein. The functional catheter may comprise acatheter for forming a fistula (e.g., a target catheter, a launchingcatheter). The second functional catheter may comprise a valve disablingdevice. The valve disabling device may comprise a valvulotome. The valvedisabling device may comprise a cutting balloon. The valve disablingdevice may comprise an atherectomy device.

In some embodiments, a method of accessing a plantar vein of a subjectcomprises injecting a quantity of contrast through a metatarsal vein,using fluoroscopy to prepare a venogram to image veins of a foot of theleg, selecting the plantar vein using the venogram, advancing aguidewire to the selected plantar vein, and tracking a functionalcatheter over the guidewire.

The metatarsal vein may be a dorsal metatarsal vein. The metatarsal veinmay be a plantar metatarsal vein. The functional catheter may comprisean element configured to snare a guidewire. The method may furthercomprise snaring a second guidewire extending from an artery using thefunctional catheter, and retracting the second guidewire. The method mayfurther comprise tracking a second functional catheter over the secondguidewire. The functional catheter may comprise a catheter for forming afistula (e.g., a target catheter, a launching catheter). The secondfunctional catheter may comprise a valve disabling device. The valvedisabling device may comprise a valvulotome. The valve disabling devicemay comprise a cutting balloon. The valve disabling device may comprisean atherectomy device.

In some embodiments, a method of accessing a plantar vein of a subjectcomprises positioning the subject in a reverse Trendelenburg position,positioning a first tourniquet above a knee of a leg, positioning asecond tourniquet above an ankle of the leg, injecting a quantity ofcontrast through a metatarsal vein, after injecting the quantity ofcontrast through the metatarsal vein, flattening the subject, usingfluoroscopy to prepare a venogram to image veins of a foot of the leg,selecting the plantar vein using the venogram, advancing a guidewire tothe selected plantar vein, removing the second tourniquet, tracking afunctional catheter over the guidewire, snaring a second guidewireextending from a vein using the functional catheter, retracting thesecond guidewire out of the foot, and tracking a second functionalcatheter over the second guidewire.

The metatarsal vein may be a dorsal metatarsal vein. The metatarsal veinmay be a plantar metatarsal vein. The functional catheter may comprise acatheter for forming a fistula. The second functional catheter maycomprise a valve disabling device. The valve disabling device maycomprise a valvulotome.

In some embodiments, a method of accessing a tibial vein of a subjectcomprises positioning a first tourniquet above a knee of a leg,positioning a second tourniquet above an ankle of the leg, injecting aquantity of contrast through a metatarsal vein, using fluoroscopy toprepare a venogram to image veins of a foot of the leg, selecting thetibial vein using the venogram, comprising advancing a guidewire to theselected tibial vein, removing the second tourniquet, and tracking afunctional catheter over the guidewire. The first tourniquet may be adifferent type than the second tourniquet.

In some embodiments, a method of aligning a catheter comprisespositioning a first catheter in a first vessel and positioning thecatheter in a second vessel. The first catheter comprises radiopaquematerial. The catheter comprises a flat rectangular radiopaque marker.The method further comprises rotating an imaging system until the firstcatheter and the catheter are in an imaging plane. Rotating the imagingsystem comprises drawing a first centerline over the first catheter,drawing a second centerline over the catheter, maximizing a distancebetween the first centerline and the second centerline, and creating asignal that the first catheter and the catheter are in the imagingplane. The method further comprises rotating the catheter until athickness of the flat rectangular radiopaque marker is at a minimum.Rotating the catheter comprises drawing a first line along a first longedge of the flat rectangular radiopaque marker, drawing a second linealong a second long edge of the flat rectangular radiopaque markeropposite the first long edge, minimizing a distance between the firstlong line and the second line, and creating a signal that the thicknessis at the minimum. The method further comprises extending a needle theimaging plane from the catheter in the second vessel, out of the secondvessel, and into the first vessel.

In some embodiments, a method of aligning a catheter comprisespositioning a first catheter in a first vessel and positioning thecatheter in a second vessel. The first catheter comprises radiopaquematerial. The catheter comprises a radiopaque marker. The method furthercomprises rotating an imaging system until the first catheter and thecatheter are in an imaging plane and rotating the catheter until athickness of the radiopaque marker is at a minimum. Rotating thecatheter comprises creating a signal that the thickness is at theminimum.

In some embodiments, a method of aligning a catheter comprisespositioning the catheter comprising a radiopaque marker in a vessel androtating the catheter until a thickness of the radiopaque marker is at aminimum. Rotating the catheter may comprise creating a signal that thethickness is at the minimum.

In some embodiments, a method of aligning a first vessel and a secondvessel in an imaging plane comprises a first catheter in the firstvessel and positioning a second catheter in the second vessel. The firstcatheter comprises radiopaque material. The second catheter comprises aradiopaque marker. The method further comprises rotating an imagingsystem until the first catheter and the second catheter are in animaging plane. Rotating the imaging system comprises drawing a firstcenterline over the first catheter, drawing a second centerline over thesecond catheter, maximizing a distance between the first centerline andthe second centerline, and creating a signal that the first catheter andthe catheter are in the imaging plane.

In some embodiments, a method of aligning a catheter comprises injectingcontrast into a first vessel, injecting contrast into a second vessel,and rotating an imaging system until the first vessel and the secondvessel are in an imaging plane. Rotating the imaging system comprisesdrawing a first line along the first vessel, drawing a second line alongthe second vessel, maximizing an area between the first line and thesecond line, and creating a signal that the first vessel and the secondvessel are in the imaging plane. The method further comprisespositioning the catheter in the second vessel. The catheter comprises aflat rectangular radiopaque marker. The method further comprisesrotating the catheter until a thickness of the flat rectangularradiopaque marker is at a minimum. Rotating the second cathetercomprises drawing a first line along a first long edge of the flatrectangular radiopaque marker, drawing a second line along a second longedge of the flat rectangular radiopaque marker opposite the first longedge, minimizing a distance between the first long line and the secondline, and creating a signal that the thickness is at the minimum. Themethod further comprises extending a needle the imaging plane from thecatheter in the second vessel, out of the second vessel, and into thefirst vessel.

In some embodiments, a method of aligning a catheter comprises injectingcontrast into a first vessel, injecting contrast into a second vessel,and rotating an imaging system until the first vessel and the secondvessel are in an imaging plane. Rotating the imaging system comprisesdrawing a first line along the first vessel, drawing a second line alongthe second vessel, maximizing an area or distance between the first lineand the second line, and creating a signal that the first vessel and thesecond vessel are in the imaging plane. The method further comprisespositioning the catheter in the second vessel.

In some embodiments, a method of aligning a first vessel and a secondvessel in an imaging plane comprises injecting contrast into the firstvessel, injecting contrast into the second vessel, and rotating animaging system until the first vessel and the second vessel are in theimaging plane.

In some embodiments, a method of aligning a catheter comprisespositioning a first catheter in a first vessel and positioning thecatheter in a second vessel. The catheter comprises a radiopaque marker.The method further comprises rotating the catheter until a thickness ofthe radiopaque marker is at a minimum, and creating a signal that thethickness is at the minimum.

In some embodiments, a method of aligning a catheter comprisespositioning a first catheter in a first vessel and positioning thecatheter in a second vessel. The catheter comprises a radiopaque marker.The method further comprises rotating the catheter until a thickness ofthe radiopaque marker is less than a value and creating a signal thatthe thickness is less than the value. The value may be less than 3 mm.The value may be less than 1 mm. The value may be less than 10 μm.

In some embodiments, a method of increasing blood perfusion to a distalextremity through retrograde flow through a venous system comprisesdiverting blood from an artery to a first vein and establishing a bloodflow loop between the first vein and a second vein.

The distal extremity may comprise a foot. The distal extremity maycomprise a hand. The distal extremity may comprise toes. The distalextremity may comprise fingers. The artery may be a posterior tibialartery. The first vein may be a medial plantar vein. The second vein maybe an anterior tibial vein. The second vein may be a lateral plantarvein. The first vein may be on a first side of a dorsal venous arch andthe second vein may be on a second side of the dorsal venous arch.

Establishing the blood flow loop may comprise disabling valves in atleast one of the first vein or the second vein. Disabling the valves inthe at least one of the first vein or the second vein may comprise usinga valvulotome. Disabling the valves in the at least one of the firstvein or the second vein may comprise using a balloon. Disabling thevalves in the at least one of the first vein or the second vein maycomprise using a stent. The stent may inhibit perfusion throughsidewalls into branch vessels.

The method may comprise establishing a second blood flow loop betweeneither the first vein or the second vein and a third vein. The thirdvein may be a lateral plantar vein. Establishing the second blood flowloop may comprise disabling valves in the third vein. Disabling thevalves in the third vein may comprise using a valvulotome. Disabling thevalves in the third vein may comprise using a balloon. Disabling thevalves in the third vein may comprise using a stent. The stent mayinhibit perfusion through sidewalls into branch vessels. Establishingthe second blood flow loop may be during a same interventionalprocedure. Establishing the second blood flow loop may be during a laterinterventional procedure.

The method may further comprise limiting an outflow in the venoussystem. Limiting the outflow in the venous system may comprisechanneling blood past bifurcating veins or side branches.

The method may further comprise embolizing bifurcating veins or sidebranches. Embolizing the bifurcating veins or side branches may compriseusing at least one of coils, microspheres, liquid embolics, or laser.

The method may further comprise applying external pressure to increaseblood pressure in the distal extremity by limiting venous outflow.Applying the external pressure may comprise using at least one of acuff, a tourniquet, or a wrap. Applying the pressure may be continuous.Applying the pressure may be intermittent.

The method may further comprise diverting blood from a second artery toat least one of the second vein, a third vein, or a fourth vein.Diverting the blood from the artery to the first vein does not includereentering the artery. The method may further comprise creating afistula between an artery in the distal extremity and a vein in thedistal extremity.

The method may further comprise creating flow loops for multiple veintargets. The multiple vein targets may include at least one vein in afirst level the distal extremity and at least one vein in a second levelof the distal extremity. The multiple vein targets may include veinsbetween at least one vein in a first level the distal extremity and atleast one vein in a second level of the distal extremity. The multiplevein targets may include perforators.

Establishing the blood flow loop may increase pressure in the blood flowloop. Increasing pressure in the blood flow loop may increase distalityof blood perfusion to a limb comprising the distal extremity.

In some embodiments, a method of increasing blood perfusion to toes of afoot through retrograde flow through a venous system comprises divertingblood from an artery to a first vein. Diverting the blood from theartery to the first vein does not include reentering the artery. Themethod further comprises establishing a blood flow loop between thefirst vein and a second vein. The first vein is on a first side of adorsal venous arch and the second vein is on a second side of the dorsalvenous arch. Establishing the blood flow loop comprises disabling valvesin at least one of the first vein or the second vein using at least oneof a valvulotome, a balloon, or a stent. The method further compriseslimiting an outflow in the venous system by channeling blood pastbifurcating veins or side branches. The method further comprisesembolizing bifurcating veins or side branches using at least one ofcoils, microspheres, liquid embolics, or laser. The method furthercomprises applying external pressure to increase blood pressure in thedistal extremity by limiting venous outflow using at least one of acuff, a tourniquet, or a wrap.

In some embodiments, a device, system, kit, etc. for increasing bloodperfusion to toes of a foot through retrograde flow through a venoussystem comprises, or alternatively consists essentially of, a firstprosthesis configured to divert blood from an artery to a first vein, atleast one of a valvulotome, a balloon, or a stent configured to disablevalves to create a blood flow loop between the first vein and a secondvein, a flow diverting stent configured to limit an outflow in thevenous system by channeling blood past bifurcating veins or sidebranches, at least one of coils, microspheres, liquid embolics, or laserconfigured to embolize bifurcating veins or side branches, and at leastone of a cuff, a tourniquet, or a wrap configured to apply externalpressure to increase blood pressure in the foot by limiting venousoutflow.

In some embodiments, devices, systems, kits, and methods for increasingblood perfusion to toes of a foot through retrograde flow through avenous system are described herein.

In some embodiments, devices, systems, kits, and methods for increasingblood perfusion to a distal extremity through retrograde flow through avenous system are described herein.

In some embodiments, a method of increasing blood perfusion to a distalextremity through retrograde flow through a venous system comprisesestablishing a blood flow loop between a first vein and a second vein.

In some embodiments, a device for diverting blood flow from a firstvessel to a second vessel and maintaining blood flow in the first vesselcomprises, or alternatively consists essentially of, a first segment anda second segment. The first segment is configured to anchor in the firstvessel. The first segment comprises a window to allow blood to flow intothe first segment, through the window, and distal in the first vessel.The second segment is configured to anchor in the second vessel. Thesecond segment is configured to allow blood to flow into the firstsegment, through the second segment, and into the second vessel.

The first segment may comprise a stent structure. At least part of thestent structure may be uncovered. The second segment may comprise thestent structure. At least one parameter of the stent structure may bedifferent between the first segment and the second segment. Theparameter may comprise a cell pattern. The second segment may comprise agraft covering. The graft covering may be generally perpendicular to alongitudinal axis of the device. The graft covering may be at an angleto a longitudinal axis of the device. The angle may be between about 10°and about 70°. The first segment may comprise a graft covering. Thegraft covering of the first segment may comprise a V-shaped cutout. Thefirst segment may be separately deployable from the second segment. Thewindow may be formed during the manufacturing process. The window may beformed in situ. The first segment may comprise a puncturable graft. Thefirst segment may comprise a stent structure configured to facilitatepuncturing. The first segment may comprise a flap configured to openradially outward. The first segment may comprise a plurality of flapsconfigured to open radially outward. The first segment may comprise abranch configured to be positioned in a branch vessel of the firstvessel. The first segment may comprise a plurality of slits configuredto open upon bending of the first segment. The device may comprise awoven braid having variable porosity along its length. The first segmentmay comprise a portion having a first porosity configured to permitperfusion of blood through the portion. The second segment may comprisea portion having a second porosity configured to divert blood throughthe portion. The first porosity may be less than 75%. The secondporosity may be greater than 60%. The device may further comprise anocclusive implant. The occlusive implant may comprise a tetherconfigured to anchor in the second segment. The second segment maycomprise a third segment configured to limit fluid flow through thedevice. The third segment may comprise a narrower diameter than thesecond segment. The first segment may comprise a flange.

In some embodiments, a method of forming a window in a device fordiverting blood flow from a first vessel to a second vessel andmaintaining blood flow in the first vessel comprises, or alternativelyconsists essentially of, implanting the device in the first vessel,extending through interstitial tissue, and into the second vessel, andinserting a guidewire through a bend in the device in the first vessel.The guidewire punctures graft material to form an opening.

The method may further comprise tracking a dilator over the guidewire towiden the opening. The dilator may have a curved tip. Inserting theguidewire through the bend may comprise exiting a catheter having anangled ramp surface. The catheter further may comprise a straight path.The method may further comprise tracking a balloon over the guidewire.The balloon may extend through the opening. The method may furthercomprise expanding the balloon. The expanded balloon may enlarge theopening. The method may further comprise anchoring the guidewire.Anchoring the guidewire may comprise expanding an anchoring balloon inthe first vessel. Inserting the guidewire through the bend may compriseforming a plurality of openings. The method may further comprisepositioning a radiopaque target outside the device and downstream of thedevice in the first vessel. The method may further comprise deploying astent through the opening.

In some embodiments, a device for diverting blood flow from a firstvessel to a second vessel and maintaining blood flow in the first vesselcomprises, or alternatively consists essentially of, a first sectioncomprising a stent structure including pores configured to allow bloodto flow into the first section, through the pores, and distal in thefirst vessel and/or into the first section, through the first section,and distal in the first vessel, and a second section configured to allowblood to flow from the first vessel into the second section, through thesecond section, and into the second vessel.

A proximal end of the first section may be configured to be placed inthe first vessel. A distal end of the first section may be configured tobe placed in the second vessel. A proximal end of the first section maybe configured to be placed in the first vessel. A distal end of thefirst section may be configured to be placed in the first vessel. Aproximal end of the second section may be configured to be placed in thefirst vessel. A distal end of the second section may be configured to beplaced in the second vessel. A length of the first section may be aboutthe same as a length of the second section. A length of the firstsection may be different than a length of the second section. A diameterof the first section may be about the same as a diameter of the secondsection. A diameter of the first section may be different than adiameter of the second section. The second section may taper from aproximal end to a distal end. A proximal section of the first sectionmay have a crescent shape. A distal section of the first section mayhave a round shape. A proximal end of the first section may beconfigured to anchor in the first vessel and may taper inwardly towardsthe distal end. The second section may extend from the distal end of thefirst section. The second segment may comprise a third segmentconfigured to limit fluid flow through the device. The third segment maycomprise a narrower diameter than the second segment. The first segmentmay comprise a flange.

In some embodiments, an implant comprises, or alternatively consistsessentially of, a first part comprising an occlusive implant configuredto occlude blood flow in a vessel and a second part tethered to thefirst part. The second part comprises an anchor configured to be coupledto a stent.

The occlusive implant may comprise at least one of an expandable mesh, asponge, a plug, a coil, a plurality of coils, an embolic liquid, ahydrogel, microspheres, or an implantable balloon. The anchor maycomprise a wire configured to form a coil upon release from a catheter.

In some embodiments, a device for diverting blood flow from a firstvessel to a second vessel and maintaining blood flow in the first vesselcomprises, or alternatively consists essentially of, a flare to beanchored in the first vessel and an elongate section extending from theflare. The elongate section is configured to be anchored in the secondvessel.

The flare may be configured to minimally extend into the first vessel.The device may comprise a plurality of flares including the flare. Theflares of the plurality of flares may be symmetrical. The flares of theplurality of flares may be asymmetrical. At least one flare of theplurality of flares may be longer than other flares of the plurality offlares. The at least one flare may be configured to be downstream ofother flares in the first vessel. The flare may be covered. The flaremay be uncovered. The elongate section may comprise a third segmentconfigured to limit fluid flow through the device. The third segment maycomprise a narrower diameter than the second segment.

In some embodiments, a device for diverting flow from branch vessels toperfuse a distal vessel comprises, or alternatively consists essentiallyof, a plurality of wires woven together to form a mesh structure. Themesh structure may have an expanded diameter between about 4 mm andabout 8 mm. The mesh structure may have a porosity between about 60% andabout 75%. The mesh structure may have a length between about 50 mm andabout 150 mm. The expanded structure may have a braid angle betweenabout 120° and about 179°. The mesh structure may have a compressionresistance between about 0.4 N/mm and about 1.1 N/mm.

The mesh structure may have a frustoconical shape. The mesh structuremay taper from the expanded diameter to a second expanded diameter. Thesecond expanded diameter may be configured to be downstream of theexpanded diameter. The mesh structure may have a chronic outward forcebetween about 0.25 N/mm and about 0.6 N/mm. Each of the plurality ofwires may have a diameter between about 50 μm and about 100 μm. Each ofthe plurality of wires may comprise shape memory material. The meshstructure may have a PPI between about 50 and about 150.

In some embodiments, a device for reducing turbulence in a vesselcomprises, or alternatively consists essentially of, a first segmenthaving a first diameter and configured to overlap a stent graft that maybe stretching the vessel and a second segment tapering from the firstdiameter to a second diameter. The device is configured to stretch thevessel in a tapered manner to provide laminar flow through the device.

The diameter may be between about 2 mm and about 10 mm. The seconddiameter may be between about 1 mm and about 8 mm. The second segmentmay have a length between about 5 mm and about 100 mm. The secondsegment may have a porosity between about 60% and about 75%. The devicemay further comprise a first radiopaque marker at a proximal end of thefirst segment. The device may further comprise a second radiopaquemarker at a transition between the first segment and the second segment.

In some embodiments, a device for limiting fluid flow through the devicecomprises, or alternatively consists essentially of, a first segmenthaving a first diameter and configured to be anchored in a first vessel,a second segment, a third segment, a fourth segment, and a fifth segmenthaving a second diameter and configured to be anchored in a secondvessel. The third segment has a third diameter less than the firstdiameter and the second diameter. The third diameter is configured tolimit fluid flow through the device. The second segment tapers from thefirst diameter to the third diameter. The fourth segment tapers from thethird diameter to the second diameter.

The first segment may be configured to divert fluid flow from the firstvessel into the second vessel. The first segment may be configured toallow fluid to continue to flow through the first vessel. The firstsegment may comprise a window. The first diameter may be less than thesecond diameter. The first diameter may be the same as the seconddiameter. The first segment may comprise a flange having a fourthdiameter larger than the first diameter. The device may comprise a stentstructure and a graft. At least part of the first segment may be devoidof the graft. The graft may have the third diameter in the thirdsegment. The stent structure may have a fourth diameter larger than thethird diameter in the third segment. The graft in the third segment maybe configured to flex inwardly in response to changes in pressure. Thegraft in the third segment may be configured to flex outwardly inresponse to changes in pressure. The first segment may be configured toanchor in a P3 segment of a popliteal artery. The first segment may beconfigured to anchor in a tibioperoneal trunk. The first diameter may bebetween about 5 mm and about 7 mm. The first diameter may be betweenabout 4 mm and about 6 mm. The second diameter may be between about 5 mmand about 7 mm. The third diameter may be between about 2.5 mm and about5 mm. At least one of the second segment or the third segment may beconfigured to provide laminar flow in the fifth segment.

In some embodiments, a device for limiting fluid flow through the devicecomprises, or alternatively consists essentially of, a first segmenthaving a first diameter and configured to be anchored in a first vessel,a second segment, and a third segment having a second diameter andconfigured to be anchored in a second vessel. The first diameter isconfigured to limit fluid flow through the device. The second segmenttapers from the first diameter to the second diameter.

The first segment may be configured to divert fluid flow from the firstvessel into the second vessel. The first segment may be configured toallow fluid to continue to flow through the first vessel. The firstsegment may comprise a window. The first segment may comprise a flangehaving a third diameter larger than the first diameter. The device maycomprise a stent structure and a graft. At least part of the firstsegment may be devoid of the graft. The graft may have the firstdiameter in the first segment. The stent structure may have a thirddiameter larger than the first diameter in the first segment. The graftin the first segment may be configured to flex inwardly in response tochanges in pressure. The graft in the first segment may be configured toflex outwardly in response to changes in pressure. The first diametermay be between about 2.5 mm and about 5 mm. The second diameter may bebetween about 5 mm and about 7 mm.

In some embodiments, a device for limiting fluid flow through the devicecomprises, or alternatively consists essentially of, a first segmenthaving a first diameter and configured to be anchored in a first vessel,a second segment extending transverse to the first segment, a thirdsegment, and a fourth segment having a second diameter and configured tobe anchored in a second vessel. The second segment has a third diameterless than the first diameter and the second diameter. The third diameteris configured to limit fluid flow through the device. The third segmenttapers from the third diameter to the second diameter.

The first segment may be configured to divert fluid flow from the firstvessel into the second vessel. The first segment may be configured toallow fluid to continue to flow through the first vessel.

In some embodiments, an implant for limiting fluid flow through a lumencomprises, or alternatively consists essentially of, a first segment, asecond segment, and a third segment. The second segment has a firstdiameter configured to limit fluid flow through the implant and to limitfluid flow through the lumen when the implant is positioned in thelumen. The first segment tapers from a second diameter configured toanchor the implant in the lumen to the first diameter. The secondsegment tapers from the first diameter to a third diameter configured toanchor the implant in the lumen.

The first diameter may be between about 2.5 mm and about 5 mm. The graftin the first segment may be configured to flex inwardly in response tochanges in pressure. The graft in the first segment may be configured toflex outwardly in response to changes in pressure. The lumen may be aflow diverting device. The lumen may be a vein. A system may comprisethe implant and a flow diverting device configured to divert fluid flowfrom a first vessel to a second vessel. The implant may be configured tobe position in the flow diverting device. The implant may be configuredto be position in the second vessel.

The methods summarized above and set forth in further detail belowdescribe certain actions taken by a practitioner; however, it should beunderstood that they can also include the instruction of those actionsby another party. Thus, actions such as “making valves in the firstvessel incompetent” include “instructing making valves in the firstvessel incompetent.”

For purposes of summarizing the invention and the advantages that may beachieved, certain objects and advantages are described herein. Notnecessarily all such objects or advantages need to be achieved inaccordance with any particular embodiment. In some embodiments, theinvention may be embodied or carried out in a manner that can achieve oroptimize one advantage or a group of advantages without necessarilyachieving other objects or advantages.

All of these embodiments are intended to be within the scope of theinvention herein disclosed. These and other embodiments will be apparentfrom the following detailed description having reference to the attachedfigures, the invention not being limited to any particular disclosedembodiment(s). Optional and/or preferred features described withreference to some embodiments may be combined with and incorporated intoother embodiments. All references cited herein, including patents andpatent applications, are incorporated by reference in their entirety.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentdisclosure are described with reference to the drawings of certainembodiments, which are intended to illustrate certain embodiments andnot to limit the invention, in which like reference numerals are usedfor like features, and in which:

FIG. 1 schematically illustrates an example embodiment of a launchingdevice directing a signal from a first body cavity to a target device ina second body cavity.

FIG. 2 is a cross-sectional representation along the dotted line B-B ofFIG. 1 .

FIG. 3 schematically illustrates an example embodiment of a launchingdevice.

FIG. 4 schematically illustrates an example embodiment of a targetdevice.

FIG. 5 schematically illustrates another example embodiment of alaunching device.

FIG. 6 schematically illustrates an example embodiment of centeringdevices for launching and/or target devices.

FIG. 7 schematically illustrates a prosthesis in place following aprocedure such as arterial-venous arterialization.

FIG. 8 is a side perspective view of an example embodiment of a devicefor providing fluid flow.

FIG. 9 shows the device of FIG. 8 in use as a shunt between two bloodvessels.

FIG. 10 is a side perspective view of another example embodiment of adevice for providing fluid flow.

FIG. 11 is a side perspective view of still another example embodimentof a device for providing fluid flow.

FIG. 12 is a side perspective view of yet another example embodiment ofa device for providing fluid flow.

FIG. 13 is a side perspective view of yet still another exampleembodiment of a device for providing fluid flow.

FIG. 14A is a schematic side cross-sectional view of an exampleembodiment of an ultrasound launching catheter.

FIG. 14B is an expanded schematic side cross-sectional view of a distalportion of the ultrasound launching catheter of FIG. 14A within thecircle 14B.

FIG. 15A is a schematic side elevational view of an example embodimentof an ultrasound target catheter.

FIG. 15B is an expanded schematic side cross-sectional view of theultrasound target catheter of FIG. 15A within the circle 15B.

FIG. 15C is an expanded schematic side cross-sectional view of theultrasound target catheter of FIG. 15A within the circle 15C.

FIG. 16 is an example embodiment of a graph for detecting catheteralignment.

FIG. 17 is a schematic side elevational view of an example embodiment ofa prosthesis delivery system.

FIG. 18 is a schematic side elevational view of an example embodiment ofa prosthesis.

FIG. 19 is a schematic side elevational view of another exampleembodiment of a prosthesis.

FIGS. 20A-20H schematically illustrate an example embodiment of a methodfor effecting retroperfusion.

FIG. 21 is a schematic perspective view of an example embodiment of anultrasound receiving transducer.

FIG. 22 is a schematic cross-sectional view of another exampleembodiment of an ultrasound receiving transducer.

FIG. 23A is a schematic perspective view of an example embodiment of avalvulotome.

FIG. 23B is a schematic perspective view of an example embodiment of areverse valvulotome.

FIG. 24 is a schematic perspective view of an example embodiment of aLeMaitre device.

FIG. 25A is a schematic side elevational view of yet another exampleembodiment of a prosthesis.

FIG. 25B is a schematic side elevational view of still another exampleembodiment of a prosthesis.

FIG. 25C is a schematic side elevational view of still yet anotherexample embodiment of a prosthesis.

FIGS. 26A and 26B schematically illustrate another example embodiment ofa method for effecting retroperfusion.

FIG. 27 schematically illustrates another example embodiment of aprosthesis and a method for effecting retroperfusion.

FIGS. 28A and 28B schematically illustrate arteries and veins of thefoot, respectively.

FIG. 29 schematically illustrates an example embodiment of ananastomosis device.

FIG. 30 schematically illustrates an example embodiment of two bloodvessels coupled by an anastomosis device.

FIG. 31A schematically illustrates an example embodiment of anarteriovenous fistula stent separate from an example embodiment of avenous stent.

FIG. 31B schematically illustrates an example embodiment of anarteriovenous fistula stent comprising an integrated venous stent.

FIG. 31C schematically illustrates an example embodiment of a fistulastent comprising an integrated venous stent.

FIGS. 32A through 32D illustrate an example method and device foridentifying and avoiding a bifurcation 1104 in a percutaneous bypassprocedure.

FIGS. 33A and 33B schematically illustrate an example procedure that canbe performed the following connection of a first vessel and a secondvessel with a needle traversing interstitial tissue.

FIGS. 34A through 35F illustrate example procedures that can beperformed when a guidewire is in a vessel.

FIGS. 36A through 36D illustrate an example method of promotingretroperfusion of blood through a vein into toes.

FIG. 37A illustrates an example of a valve disabling device in aradially expanded state.

FIG. 37B is a flattened side view of the valve disabling device of FIG.37A.

FIG. 37C is an expanded view of the flattened side view of the valvedisabling device of FIG. 37A in the area identified by the circle 37C inFIG. 37B.

FIG. 37D is an end view of the valve disabling device of FIG. 37Aflattened as shown in FIG. 37B.

FIG. 37E is an end view of the valve disabling device of FIG. 37A in aradially contracted state.

FIG. 37F is a side view of the valve disabling device of FIG. 37A in aradially contracted state.

FIG. 37G is another side view of the valve disabling device of FIG. 37Ain a radially contracted state and circumferentially rotated compared toFIG. 37F.

FIG. 37H is a side view of the valve disabling device of FIG. 37A in aradially expanded state.

FIG. 371 is another side view of the valve disabling device of FIG. 37Ain a radially expanded state and circumferentially rotated compared toFIG. 37H.

FIG. 37J is a cross-sectional end view of the valve disabling device ofFIG. 37A in a radially expanded state taken along the line 37J-37J ofFIG. 37H.

FIGS. 37Ki through 37Nii illustrate example procedures that can beperformed using the valve disabling device of FIG. 37A.

FIG. 38A schematically illustrates an example of a distal end of acatheter.

FIGS. 38B through 38D illustrate an example procedure that can beperformed using the distal end of the catheter of FIG. 38A.

FIGS. 38Ei and 38Eii illustrates an example of a distal end of acatheter.

FIG. 38F illustrates an example of a portion of a catheter.

FIG. 38G illustrates another example of a portion of a catheter.

FIG. 39A is a perspective view of an example of a portion of a targetcatheter.

FIG. 39B is a side view of the target catheter of FIG. 39A in a firststate.

FIG. 39C is a side view of the target catheter of FIG. 39A in a secondstate.

FIGS. 39D-39I schematically illustrate an example method of using thetarget catheter of FIG. 39A.

FIG. 40A is a perspective view of an example handle for deploying atubular structure.

FIG. 40B is an expanded perspective cross-sectional view of a portion ofthe handle of FIG. 40A.

FIG. 40C is a perspective view of the handle of FIG. 40A in a deployedstate.

FIG. 40D is an expanded perspective cross-sectional view of a portion ofthe handle of FIG. 40A in a deployed state.

FIG. 41A is a perspective view of an example handle for deploying atubular structure.

FIG. 41B is an expanded perspective partially transparent view of aportion of the handle of FIG. 41A.

FIGS. 41C to 41Eiii show an example method of operating the handle ofFIG. 41A.

FIG. 42A is a top view of an example embodiment of a launching device.

FIG. 42B is a schematic top, side, and distal end perspective view of adistal portion of the launching device of FIG. 42A.

FIG. 42Bi is a schematic side view of an example radiopaque marker.

FIG. 42C is a schematic expanded top view of the distal portion of thelaunching device of FIG. 42A.

FIGS. 42Ci-42Ciii illustrate an example catheter including a profileattached to the needle.

FIG. 42D is a schematic side view of the distal portion of the launchingdevice of FIG. 42A.

FIGS. 43A-43N schematically illustrate an example method of using alaunching device including the distal portion of the launching device ofFIG. 42A.

FIGS. 430 i -430 vi illustrate an example implementation of alignmentusing software.

FIGS. 44A-44J schematically illustrate anatomy of an example foot.

FIG. 45 shows example components of a kit that may be used for pedalaccess.

FIGS. 46A-46K show example procedures for performing an ascendingvenogram.

FIG. 47A is a perspective view of a portion of an example cutting snaresystem.

FIGS. 47Bi and 47Bii are side views of another example cutting snaresystem.

FIGS. 47Ci-47Ciii are side views of another example cutting snaresystem.

FIG. 47Civ is a side view of yet another example cutting snare system.

FIGS. 47Di-47Dv are side views of still another example cutting snaresystem.

FIGS. 47Ei-47Eiii are side views of still yet another example cuttingsnare system.

FIG. 47Eiv is a side view of another example cutting snare system.

FIGS. 47Fi and 47Fii are side views of yet another example cutting snaresystem.

FIGS. 47Gi-47Giii are side views of still another example cutting snaresystem.

FIG. 48A illustrates an example image of a foot after a venousarterialization procedure.

FIG. 48B illustrates another example image of a foot after a venousarterialization procedure.

FIG. 49 illustrates an example method of providing blood flow to aplurality of veins.

FIG. 50 illustrates a method of using embolization coils to preventvessel steal and redirect blood distally.

FIG. 51A is a partial cross-section of an example device providing fluidflow from a first vessel to a second vessel and through the firstvessel.

FIG. 51B is a side view of another example device providing fluid flowfrom a first vessel to a second vessel and through the first vessel.

FIG. 51C is a side view of yet another example device providing fluidflow from a first vessel to a second vessel and through the firstvessel.

FIG. 51D is a side view of still another example device providing fluidflow from a first vessel to a second vessel and through the firstvessel.

FIG. 52A is a side view of still another example device providing fluidflow from a first vessel to a second vessel and through the firstvessel.

FIG. 52Bi is a side view of still yet another example device providingfluid flow from a first vessel to a second vessel and through the firstvessel.

FIG. 52Bii is an example cross-sectional view of the device of FIG. 52Biacross the line 52Bx-52Bx.

FIG. 52Biii is another example cross-sectional view of the device ofFIG. 52Bi across the line 52Bx-52Bx.

FIG. 52Ci is a side view of another example device providing fluid flowfrom a first vessel to a second vessel and through the first vessel.

FIG. 52Cii is a cross-sectional view of the device of FIG. 52Ci acrossthe line 52Cii-52Cii.

FIG. 52D is a side view of yet another example device providing fluidflow from a first vessel to a second vessel and through the firstvessel.

FIG. 53A is a side view of still another example device providing fluidflow from a first vessel to a second vessel and through the firstvessel.

FIGS. 53Bi-53Biii illustrate an example method of in situ formation ofan example device providing fluid flow from a first vessel to a secondvessel and through the first vessel.

FIG. 53Ci shows an example cell pattern for a stent structure of afenestrated device.

FIG. 53Cii shows an example of the stent structure of FIG. 53Cipartially covered in graft and including a window.

FIG. 53Di illustrates an example method of in situ formation of anexample device providing fluid flow from a first vessel to a secondvessel and through the first vessel.

FIG. 53Dii shows an example tapered segment usable with the device ofFIG. 53Di.

FIG. 53Diii shows another example tapered segment usable with the deviceof FIG. 53Di.

FIGS. 53Ei and 53Eii illustrate an example method of aligning apuncturer for in situ formation of an example device providing fluidflow from a first vessel to a second vessel and through the firstvessel.

FIG. 54A is a side view of yet still another example device providingfluid flow from a first vessel to a second vessel and through the firstvessel.

FIG. 54Bi is a side view of still yet another example device providingfluid flow from a first vessel to a second vessel and through the firstvessel.

FIG. 54Bii is a side view of another example device providing fluid flowfrom a first vessel to a second vessel and through the first vessel.

FIG. 54C is a side view of yet another example device providing fluidflow from a first vessel to a second vessel and through the firstvessel.

FIG. 55A is a side view of still another example device providing fluidflow from a first vessel to a second vessel and through the firstvessel.

FIG. 55B shows the device of FIG. 55A positioned in a first vessel,extending through interstitial tissue, and into a second vessel.

FIG. 55C shows yet still another example device providing fluid flowfrom a first vessel to a second vessel and through the first vessel.

FIG. 55D is a distal end view of the device of FIG. 55C implanted in thefirst vessel and the second vessel.

FIG. 55Ei is a top view of a device sharing features of the device ofFIGS. 55C and 55D.

FIG. 55Eii is a top view of another device sharing features of thedevice of FIGS. 55C and 55D.

FIG. 55F shows yet still another example device providing fluid flowfrom a first vessel to a second vessel and through the first vessel.

FIG. 55G is a top view of the device of FIG. 55F.

FIG. 56A is a side view of still another example device providing fluidflow from a first vessel to a second vessel and through the firstvessel.

FIG. 56B is a graph showing flow through a parent vessel and a sidebranch with and without a device of FIG. 56A for different values ofporosity of the device.

FIG. 57A illustrates an example device for directing flow below anankle.

FIG. 57Bi illustrates a first example of blood flow through a veinproximate to an ankle.

FIG. 57Bii illustrates a second example of blood flow through a veinproximate to an ankle.

FIGS. 57Ci-57Ciii illustrate example variations on woven flow divertingdevices sharing features with the device of FIG. 57A.

FIG. 57Di illustrates a device in which a portion of the graft coveringis perforated with a plurality of openings.

FIG. 57Dii is a schematic side view of the device of FIG. 57Di showingthe effect of the porous region on fluid flow.

FIG. 57E is a schematic spectrum of porosity showing the effect ofporosity on steal.

FIG. 57Fi is a side view of another example device configured to providefluid flow from a first vessel to a second vessel and through the firstvessel.

FIG. 57Fii is an expanded view of the device of 57Fi in the area 57Fii.

FIG. 57Fiii shows the device positioned in a first vessel, extendingthrough interstitial tissue, and into a second vessel.

FIG. 57Fiv is an expanded view of the device of 57Fiii in the area57Fiv.

FIG. 58A is a side view of an example occlusive implant.

FIGS. 58Bi-58Biii illustrate an example method of in situ coupling ofthe occlusive implant of FIG. 58A and an example device providing fluidflow from a first vessel to a second vessel and through the firstvessel.

FIG. 58C is a side view of an example occlusive implant systemcomprising the occlusive implant of FIG. 58A.

FIG. 59Ai illustrates a third example of blood flow through a veinproximate to an ankle.

FIG. 59Aii illustrates a fourth example of blood flow through a veinproximate to an ankle.

FIG. 59B illustrates the device of FIG. 59Aii overlapping a stent graft.

FIG. 60 is a partially transparent view showing certain vasculature of aleft lower leg.

FIG. 61A illustrates an example of a prosthesis that can be placedupstream of an occlusion.

FIG. 61B illustrates another example of a prosthesis that can be placedupstream of an occlusion.

FIG. 61C illustrates yet another example of a prosthesis that can beplaced upstream of an occlusion.

FIG. 61D illustrates still another example of a prosthesis that can beplaced upstream of an occlusion.

FIG. 62A illustrates an example of a prosthesis that can be placedupstream of an occlusion.

FIG. 62B illustrates another example of another prosthesis that can beplaced upstream of an occlusion.

FIG. 62C illustrates yet another example of a prosthesis that can beplaced upstream of an occlusion.

FIG. 62D illustrates still another example of a prosthesis that can beplaced upstream of an occlusion.

FIG. 63A illustrates an example of a prosthesis that can be placedupstream of an occlusion.

FIG. 63B illustrates another example of a prosthesis that can be placedupstream of an occlusion.

FIG. 63C illustrates yet another example of a prosthesis that can beplaced upstream of an occlusion.

FIG. 64 illustrates an example of a flow limiting implant.

FIG. 65 illustrates still another example of a prosthesis that can beplaced upstream of an occlusion.

DETAILED DESCRIPTION

Although certain embodiments and examples are described below, theinvention extends beyond the specifically disclosed embodiments and/oruses and obvious modifications and equivalents thereof. The scope of theinvention herein disclosed should not be limited by any particularembodiment(s) described below.

Minimally invasive surgery could provide a means for treating a broaderrange of patients, including those currently excluded from standardsurgical techniques. One such procedure is percutaneous in situ coronaryvenous arterialization (PICVA), which is a catheter-based coronarybypass procedure in which the occlusion in the diseased artery is“bypassed” by creation of a channel between the coronary artery and theadjacent coronary vein. In this way, the arterial blood is diverted intothe venous system and can perfuse the cardiac tissue in a retrogrademanner (retroperfusion) and restores blood supply to ischemic tissue.Some example devices and methods for performing procedures like PICVAare described in PCT Pub. No. WO 99/049793 and U.S. Patent Pub. No.2004/0133225, which are hereby incorporated by reference in theirentirety.

Successfully performing a minimally invasive procedure of divertingblood flow from the coronary artery to the adjacent vein heretofore hashad a low success rate, most often due to inability to properly targetthe vein from the artery. Without the proper systems and methods, suchprocedures (e.g., attempting to target the vein by combination of X-rayfluoroscopy and an imaging ultrasound probe located on the distal tip ofthe catheter e.g., as described in U.S. Patent Pub. No. 2004/0133225)are often doomed to failure before even starting. Indeed, such anarrangement can be difficult to navigate, and localization of theadjacent vein can require considerable skill on the part of theclinician. Improvements in the systems and methods for targeting, suchas those using the catheters described herein, can enable proceduressuch as PICVA and transvascular surgery in general. Without suchimprovements, such percutaneous techniques will remain peripheral toconventional surgical open-heart and other types of bypass operations.

The present application, according to several embodiments, describesmethods and systems usable in minimally invasive surgical procedures,which can reduce performance of conventional surgery to treat conditionssuch as coronary heart disease and critical limb ischemia. For example,patients who might otherwise be unable to receive surgery such ascoronary bypass surgery or peripheral arterial bypass surgery can betreated, and the amount of surgical trauma, the risk of infection,and/or the time to recovery may be reduced or significantly reduced incomparison to conventional surgery.

FIG. 1 schematically illustrates an example embodiment of a launchingdevice 10 directing a signal from a first body cavity 30 to a targetdevice 20 in a second body cavity 35. The launching device 10 comprisesa signal transmitter 12. The launching device 10 may comprise, forexample, a catheter including an elongate flexible rod-like portion anda tip portion, and may provides a conduit for administering therapywithin the body of a patient. The launching device 10 may be suitablefor location and movement through a first cavity or vessel 30 (e.g.,heart chamber, coronary artery, coronary vein, peripheral artery,peripheral vein) within a patient's body. The elongate portion of thelaunching device 10 comprises an outer sheath 11 that encloses a space,defining a lumen 13. The space within the lumen 13 may be suitablypartitioned or subdivided as necessary so as to define channels foradministering therapy, controlling the positioning of the launchingdevice 10, etc. Such subdivision may, for example, be achieved eitherlongitudinally or concentrically in an axial fashion.

The launching device 10 comprises a signal transducer 12. The signaltransducer 12 is configured to provide or emit a signal 40 that isdirected outwards from the launching device 10. In the embodiment shownin FIG. 1 , the signal 40 is directed radially outward from thelaunching device 10 in a direction that is perpendicular to thelongitudinal axis of the launching device 10. As mentioned in greaterdetail below, in some embodiments, the direction of the signal 40 neednot be perpendicular and can be directed at an angle to the longitudinalaxis of the launching device 10. The signal transducer 12 may therebyform at least a portion of a signal generating means.

The signal transducer 12 is connected to signal transmitter 50. Thesignal transmitter 50 can be suitably selected from ultrasound orappropriate electromagnetic sources such as a laser, microwaveradiation, radio waves, etc. In some embodiments, as described infurther detail below, the signal transmitter 50 is configured togenerate an ultrasound signal, which is relayed to the signal transducer12, which in turn directs the signal 40 out of the first body cavity 30into the surrounding tissue.

A target device 20 is located within an adjacent second body cavity orvessel 32 (e.g., heart chamber, coronary artery, coronary vein,peripheral artery, peripheral vein) within a patient's body. The firstand second body cavities 30, 32 are separated by intervening tissue 34,sometimes referred to as interstitial tissue or a septum. The first andsecond body cavities 30, 32 are located next to each other in a parallelfashion for at least a portion of their respective lengths. For example,many of the veins and arteries of the body are known to run in parallelwith each other for at least a portion of their overall length.

The target device 20 can assume a similar arrangement to that of thelaunching device 10. For example, the target device 20 can comprise acatheter including an elongate flexible rod-like portion and a tipportion. For another example, fine movement and positioning of thetarget device 20 within the body cavity 32 can be achieved. For yetanother example, the target device 20 may comprise an outer sheath 21that encloses a space, defining a lumen 23. The lumen 23 can be suitablypartitioned, for example as with the launching device 10.

The target device 20 comprises a receiving transducer 22 configured toreceive the signal 40 from the transducer 12 of the launching device 10.The receiving transducer 22 makes up at least a portion of a signaldetection means. In use, when the receiving transducer 22 receives thesignal 40 transmitted from the signal transducer 12, the receivingtransducer 22 transmits the received signal to a signal detector 60. Thesignal detector 60 is configured to provide an output reading to theuser of the system, for example via an output display 61. The outputdisplay 61 may be a visual display, an audio display (e.g., beeping oremitting some other sound upon receipt of a signal), etc.

In this way, the transmission and detection of the directed signal 40can allow for the navigation and positioning of the launching device 10relative to the target device 20. In use, the launching device 10 andthe target device 20 can be maneuvered by the user of the system untilthe output display 61 indicates that signal 40 is being received by thetarget device 40.

In some embodiments, the signal 40 comprises or is an ultrasound signal.The signal 40 is directional and is emitted by the signal transducer 12in the shape of a narrow cone or arc (e.g., with the width of the signalband increasing as the distance from the signal transducer 12increases). As such, the precision of alignment between the launchingdevice 10 and the target device 20 depends not only upon signaldetection, but also upon the distance between the two devices, as thesignal beam width is greater at greater distances. This level of erroris referred to as “positional uncertainty.” A certain level of tolerancecan exist for positional uncertainty; however, if therapy is to bedirected with precision, the amount of uncertainty should be reduced orminimized. For example, if the diameter d of the signal transducer 12 is1 mm and the frequency of the ultrasound signal is 30 MHz, then thepositional uncertainty x (e.g., the margin of error on either side of acenter line) is 1 mm at a perpendicular separation of 5 mm between thelaunching device 10 and the target device 20. For clinical applications,the positional uncertainty generally should not exceed around ±5 mm (fora total signal beam width of 10 mm at the point of reception). In someembodiments, the positional uncertainty is between about ±0.01 mm andabout ±4.50 mm or between about ±0.1 mm and about ±2 mm. In someembodiments, the positional uncertainty does not exceed about ±1 mm.

The strength of the signal 40 can be a factor in detection, and signalstrength generally diminishes as the distance between the launchingdevice 10 and the target device 20 increases. This distance is in partdetermined by the amount of intervening tissue 34 between the devices10, 20. By way of example, if the signal 40 is an ultrasound signal,significant deterioration of signal can be expected when the launchingdevice 10 and the target device 20 a separated by more than about 20 mmof solid tissue (e.g., the intervening tissue 34). The density of theintervening tissue 34 may also have an effect upon the deterioration ofsignal 40 over distance (e.g., denser tissue deteriorating the signalmore than less dense tissue).

The frequency of the ultrasound signal may also affect the thickness ofthe signal transducer, which for a standard ultrasound ceramictransducer (e.g., a piezoelectric transducer (PZT)) is 0.075 mm at 30MHz.

FIG. 2 is a cross-sectional representation along the dotted line B-B ofFIG. 1 . The correct orientation of the launching device relative to thetarget device can be a factor in detection, as the line of orientation41 can determine where the therapy is to be applied. The clinical needfor precisional placing of therapy in a patient may function better ifthe directional signal 40 is linked to the means for delivering therapy(e.g., being parallel and longitudinally offset). For example, in thisway the user of the system can administer therapy to the correctlocation by ensuring that the launching device 10 and the target device20 are correctly positioned via transmission and reception of the signal40. The orientation line 41 in FIG. 2 denotes not only the direction ofsignal travel but also the path along which therapy can be administeredto the patient.

FIG. 3 schematically illustrates an example embodiment of a launchingdevice 10. The launching device 10 comprises a signal transducer 120that is oriented at an oblique angle relative to the longitudinal axisof the launching device 10. The signal 40 is transmitted at an anglethat is in the direction of travel (e.g., forward travel, transversetravel) of the launching device 10 as the launching device enters a bodycavity 30 (FIGS. 1 and 2 ). In some embodiments, the beam angle is aboutperpendicular to the longitudinal axis of the launching device 10. Insome embodiments, the beam angle is between about 20° and about 60° tothe perpendicular, between about 30° and about 50° to the perpendicular,or about 45° to the perpendicular, when 0° corresponds to thelongitudinal axis of the launching device 10 in the direction of travel.

The launching device 10 comprises a hollow needle or cannula 17, whichis an example means for administering therapy. During travel of thelaunching device 10, the hollow needle 17 is located in an undeployed orretracted state within the lumen 13 of launching device 10. The hollowneedle 17 may be deployed/extended from the launching device 10 via anaperture 16 in the outer sheath 11 at a time deemed appropriate by theuser (e.g., upon detection of the signal 40 by the target device 20).The aperture 16 can allow fluid communication between the lumen 13 andthe body cavity 30 (FIG. 1 ). As illustrated by the example embodimentof FIG. 3 , the hollow needle 17 may travel along a path that isparallel to the direction of the signal 40. The hollow needle 17 may beused to pierce the intervening tissue 34 (FIG. 1 ). In some embodiments,the hollow needle 17 makes a transit across the entirety of theintervening tissue 34, and in doing so allows the launching device 10 toaccess the second body cavity 32 (FIG. 2 ). If desired, the pathway madeby the hollow needle 17 through the intervening tissue 34 can besubsequently widened to allow fluid communication between the first bodycavity 30 and the second body cavity 32.

Therapeutic means suitable for use in several embodiments can comprise,for example, devices and/or instruments selected from the groupconsisting of a cannula, a laser, a radiation-emitting device, a probe,a drill, a blade, a wire, a needle, appropriate combinations thereof,and the like.

In some embodiments, the hollow needle 17 comprises a sensor 19, whichmay assist in further determining positional information of the tip ofthe hollow needle 17 relative to the launching device 10. In someembodiments, the sensor 19 is configured to detect changes inhydrostatic pressure. Other sensors that are suitable for use in thesystems and methods described herein can include temperature sensors,oxygenation sensors, and/or color sensors.

Optionally, the hollow needle 17 can comprise an additional signaltransducer 122. In the embodiment shown in FIG. 3 , the signaltransducer 122 is located near the tip of the hollow needle 17 on theend of a guidewire 14. The signal transducer 122 can also oralternatively located on the hollow needle 17 if desired. In use, thesignal transducer 122 is driven with a short transmit pulse thatproduces a directional signal or a non-directional signal pulse. Thesignal pulse can be detected by the receiving transducer 22 mounted onthe target device 20. The distance from the guidewire 14 or hollowneedle 17 to the receiving transducer 22 and hence the target device 20can be at least partially determined time based on the delay between thetransmission of the signal pulse from the signal transducer 122 andreceipt of the signal pulse on the receiving transducer 22.

FIG. 4 schematically illustrates an example embodiment of a targetdevice 20. In the embodiment shown in FIG. 4 , the target device 20 islocated within a body cavity 32. As mentioned above, the target device20 comprises a receiving transducer 22 for receiving the signal 40. Thereceiving transducer 22 can be unidirectional (e.g., capable ofreceiving a signal from one direction only) or omnidirectional (e.g.,capable of receiving a signal from any direction). Arrow A shows thereversed direction of blood flow after an arterial-venousarterialization (also called PICVA) has been effected. The target device20 comprises an omnidirectional ultrasound signal receiving transducer60. An optional reflecting cone 601 can direct the signal 40 onto adisc-shaped receiving transducer 60. An acoustically transparent window602 can separate the reflecting cone 601 from the receiving transducer60. In some embodiments, an omnidirectional ultrasound signal receivingtransducer can be obtained by locating a cylinder of a flexiblepiezoelectric material such as polyvinyldifluoride (PVDF) around theouter sheath of the target device 20. In such a way, the cylinder canact in a similar or equivalent manner to the receiving transducer 60.

In the embodiment illustrated in FIG. 4 , the target device 20 comprisesan optional channel 25 for administering an agent, such as a therapeuticagent, to a patient. In some embodiments, the channel 25 functions as aconduit to allow application of a blocking material 251 that serves toat least partially obstruct or occlude the body cavity 32. The blockingmaterial 251 can be suitably selected from a gel-based substance. Theblocking material 251 can also or alternatively include embolizationmembers (e.g., balloons, self-expanding stents, etc.). The placement ofthe blocking material 251 can be directed by movement of the targetdevice 20. The presence of a guide member 24 within the lumen 23 of thetarget device 20 can allow the user to precisely manipulate the positionof the target device 20 as desired.

Referring again to FIG. 2 , the launching device 10 comprises a signaltransducer 12 that may optionally be oriented so that the signal 40 istransmitted at an angle other than perpendicular to the signaltransducer 12. FIG. 5 schematically illustrates another exampleembodiment of a launching device 10. In some embodiments, for examplethe launching device 10 shown in FIG. 5 , the signal transducer is inthe form of a signal transducer array 123. The signal transducer array123 comprises a plurality of signal transducer elements 124, which canbe oriented collectively to at least partially define a signal beamwidth and angle relative to the launching device 10. Smaller size of theelements 124 can allow the signal transducer 123 to not occupy asignificant proportion the lumen 13 of the launching device 10.

The embodiment shown in FIG. 5 may be useful for ultrasound beam-formingsignaling. FIG. 5 shows an array of signal transducer elements 124 thatare separately connected to a transmitter 50 via delays 51, which allowsthe signals to each element 124 to be delayed relative to each other.The delays can provide or ensure that the ultrasound wavefronts fromeach element 124 are aligned to produce a beam of ultrasound 40 at thedesired angle. In some embodiments, for example in which the signal 40comprises visible light, an array of LEDs can also or alternatively beused.

FIG. 6 schematically illustrates an example embodiment of centeringdevices for launching and/or target devices 10, 20. To assist in theprocess of alignment between the launching device 10 in the first bodycavity 30 and the target device 20 in the second body cavity 32, one orboth of the devices 10, 20 may comprise means for centering therespective devices within their body cavities.

In some embodiments, the centering means comprises an inflatable bladderor balloon 111 that is located in the lumen 13, 23 when in an undeployedstate and, when the device 10, 20 reaches the desired location withinthe patient, can be inflated. The balloon 111 can be disposed on anouter surface of the outer sheath 11, 21. The balloon 111 can be annularin shape such that it at least partially surrounds the device 10, 20 ina toroidal or doughnut-like fashion. The balloon 111 can be arrangedsuch that it inflates on only one side or only on two opposite sides ofthe device 10, 20. As illustrated in FIG. 6 , the balloon 111 isdeployed on one side of the launching device 10.

In some embodiments, the centering means comprises one or more loopstructures 112 located either in the lumen 13, 23 or within recessesmade in the outer sheath 11, 21 when in an undeployed or retractedstate. When the device 10, 20 reaches the desired location within thepatient, the one or more loop structures 112 can be expanded radiallyoutwardly from the device 10, 20, thereby centering the device 10, 20within the body cavity 30, 32. Outward expansion of the loop structures112 can be suitably effected by compression of a length of wire, forexample, such that it bows outwardly from the outer sheath 11, 21. Acentering device that adopts this conformation may comprise a pluralityof compressible lengths of wire or other suitable flexible materialarranged in parallel at radially spaced intervals around the peripheryof the outer sheath 11, 21. Compression of the plurality of wires can beinduced by way of a sliding member (not shown) located proximally and/ordistally near to the ends of the plurality of wires. The sliding memberis capable of translational movement along the longitudinal axis of thedevice 10, 20. As illustrated in FIG. 6 , the target device 20 comprisesfully deployed centering means 112 that has allowed the target device 20to be centered within the body cavity 32.

Other possible means for centering the devices 10, 20 within the bodycavities 30, 32 include, but are not limited to, expandableChinese-lantern type devices, reversibly expandable stents, coils,helices, retractable probes or legs, combinations thereof, and the like.

In some embodiments, the centering means or other means (e.g., balloons,metal stand-offs having differing lengths, etc.) can be used to orientthe devices 10, 20 within the body cavities 30, 32 other than in thecenter or substantially the center of the body cavities. For example,the device 10 may be oriented proximate to the wall of the body cavity30 where the needle 17 will exit the body cavity 30, which can, forexample, provide a shorter ultrasound signal path and/or reduce errordue to the needle 17 traversing intraluminal space. For another example,the device 10 may be oriented proximate to the wall of the body cavity30 opposite the wall of the body cavity 30 where the needle 17 will exitthe body cavity 30, which can, for example, provide a firm surface forthe needle 17 to push against. For yet another example, the device 20may be oriented proximate to the wall of the body cavity 32 where theneedle 17 will enter the body cavity 32, which can, for example, providea shorter ultrasound signal path. Other device orientations that areneither centered nor proximate to a vessel wall are also possible (e.g.,some fraction of the diameter away from the wall and/or the center ofthe lumen, such as ½, ⅓, ¼, etc.).

Example

The methods and systems described herein demonstrate particular utilityin cardiovascular surgery according to several embodiments. Certainaspects are further illustrated by the following non-limiting example,in which the system is used by a clinician to perform the procedure ofarterial-venous connection (PICVA) so as to enable retroperfusion ofcardiac tissue following occlusion of a coronary artery.

The launching catheter 10 is inserted into the occluded coronary arteryby standard keyhole surgical techniques (e.g., tracking over aguidewire, tracking through a guide catheter). The target catheter 20 isinserted into the coronary vein that runs parallel to the coronaryartery by standard keyhole surgical techniques (e.g., tracking over aguidewire, tracking through a guide catheter). The coronary vein is notoccluded and, therefore, provides an alternative channel for blood flowto the cardiac muscle, effectively allowing the occlusion in thecoronary artery to be bypassed.

The launching catheter 10 comprises a PZT ultrasound transducer 12(e.g., available from CTS Piezoelectric Products of Albuquerque, N.Mex.) that is oriented such that a directional ultrasound beam istransmitted in this example at a 45° angle (relative to the longitudinalaxis of the launching device), preferably in the direction of blood flowin the artery 30, although other angles including about 90° are alsopossible. The ultrasound transducer 12 is activated, and in this examplea 30 MHz directional ultrasound signal 40 is transmitted from thelaunching catheter 10, although other frequencies are also possible. Thetarget catheter 20 comprises an omnidirectional ultrasound receivingtransducer 60. To assist with localization of both the launchingcatheter 10 and the target catheter 20, both catheters 10, 20 comprisecentering or orienting means, in this example in the form of an annularinflatable balloon 111, although other or absence of centering ororienting means are also possible. The centering means 111 on thelaunching catheter 10 is deployed by the clinician when the launchingcatheter 10 is deemed to be in an appropriate location close to the siteof the occlusion within the coronary artery 30. This may be determinedvia standard fluoroscopic imaging techniques and/or upon physicalresistance. The target catheter 20 is then moved within the adjacentcoronary vein 32 until the directed ultrasound signal 40 is detected bythe signal receiving transducer 60. To enable more precise alignmentbetween the launching catheter 10 and the target catheter 20, thecentering means 111 on the target catheter 20 can be deployed eitherbefore or after the signal 40 is detected.

Upon reception of the transmitted signal 40, the clinician can becertain that the launching catheter 10 and the target catheter 20 arecorrectly located, both rotationally and longitudinally, within theirrespective blood vessels 30, 32 to allow for the arterial-venousconnection procedure to commence. The target catheter 20 may be used toblock blood flow within the coronary vein 32 via administration of a gelblocking material 251 though a channel 25 in the target catheter 20. Theblocking material 251 may be administered at a position in the coronaryvein 32 that is downstream in terms of the venous blood flow relative tothe location of the receiving signal transducer 60.

The clinician may then initiate arterial-venous connection by deployinga hollow needle 17 from the launching catheter 10 substantially along apath that is parallel and close to the path taken by the ultrasoundsignal 40 though the intervening tissue 34 between the coronary artery30 and the coronary vein 32, or the hollow needle 17 may traverse a paththat intercepts the path of the ultrasound signal at a point within thecoronary vein 32. The hollow needle 17 optionally comprises a sensor 19near its tip that is configured to detect changes in hydrostaticpressure or Doppler flow such that the user can monitor the transitionfrom arterial pressure to venous pressure as the hollow needle 17 passesbetween the two vessels 30, 32. The hollow needle 17 optionallycomprises a guidewire 14 in a bore or lumen of the hollow needle 17during deployment. Once the hollow needle 17 and guidewire 14 havetraversed the intervening tissue 34, the hollow needle 17 may beretracted back into the lumen 13 of the launching catheter 10, leavingthe guidewire 14 in place. In some embodiments, once the hollow needle17 has traversed the intervening tissue 34, the user can separately passthe guidewire 14 through the bore or lumen of the hollow needle 17 andthen retract the needle 17 into the launching catheter 10.

The clinician withdraws the launching catheter 10 from the patient,leaving the guidewire 14 in place. A further catheter device is thenslid along the guidewire 14. FIG. 7 schematically illustrates aprosthesis 26 such as an expandable stent 26 in place following aprocedure such as arterial-venous arterialization. Further detail aboutpossible prostheses including stents and stent-grafts are providedbelow. The stent 26 may be deployed to widen the perforation in theintervening tissue 34 between the coronary artery 30 and the coronaryvein 32, in which the interrupted arrow A shows the direction of bloodflow through the stent 26 between the first and second body cavities 30,32 (e.g., arterial blood is thereby diverted into the venous system andis enabled to retroperfuse the cardiac muscle tissue). The stent 26 canblock flow upwards in the cavity 32, forcing blood flow in the cavity 32to be in the same direction as blood flow in the cavity 30. Graftmaterial of the stent 26 can form a fluid-tight lumen between the cavity30 and the cavity 32. The target catheter 20 is withdrawn from thepatient, leaving the blocking material 251 in position. Optionally, afurther block or suture may be inserted into the coronary vein toinhibit or prevent reversal of arterial blood flow, as described infurther detail herein.

Whilst the specific example described above is with respect tocardiovascular surgery, the methods and systems described herein couldhave far reaching applications in other forms of surgery. For example,any surgery involving the need to direct therapy from one body cavity(e.g., for treatment of peripheral artery disease) towards anotheradjacent body cavity could be considered. As such, applications in thefields of neurosurgery, urology, and general vascular surgery are alsopossible. The type of therapy need not be restricted to formation ofchannels between body cavities. For instance, the methods and systemsdescribed herein may also be used in directing techniques such ascatheter ablation, non-contact mapping of heart chambers, the deliveryof medicaments to precise areas of the body, and the like.

Certain techniques for effectively bypassing an occlusion in an arteryby percutaneous surgery are described above. These techniques includecreating a channel or passage between a first passage, such as an arteryupstream of an occlusion, a vein, or a heart chamber, and a secondpassage, such as an artery, vein, or heart chamber, proximate to thefirst passage to interconnect the first and second passages by a thirdpassage. Fluid such as blood may be diverted from the first passage intothe second passage by way of the interconnecting third passage. Inembodiments in which the first passage includes an artery and the secondpassage includes a vein, the arterial blood can perfuse into tissue in aretrograde manner (retroperfusion).

As described above, an interconnecting passage between first and secondbody passages can be created by, for example, deploying a needleoutwards from a first catheter located within the first passage, so thatthe needle traverses the interstitial tissue or septum between the firstand second passages. A second catheter may be located in the secondpassage, so as to provide a target device which receives a signal, forexample an ultrasound signal, transmitted from the first catheter. Bymonitoring the received signal, the position of the first catheter withrespect to the second catheter can be determined so as to ensure thatthe needle is deployed in the correct position and orientation to createa passage for fluid flow between the first and second passages.

In order to provide or maintain the flow of blood thorough theinterconnecting passage or channel, a structure including a lumen may beinserted in the passage to support the interstitial tissue and/or toinhibit or prevent the passage from closing. The tube may, for example,include a stent expanded in the channel using a balloon catheter orself-expansion, as described herein. A catheter to deliver thestructure, for example a balloon catheter or catheter that allowsself-expansion, may be guided to the channel by a guidewire deployed inthe passage by the first catheter.

Passages such as arteries, veins, and heart chambers can pulsate as theheart beats, for example due to movement of heart walls, peripherallimbs, and/or fluctuations in pressure within the passages themselves.This pulsation can cause movement of the passages relative to eachanother, which can impose stress on a structure within aninterconnecting passage therebetween. This stress may be large incomparison to stress experienced by a structure within a single passage.Stress can lead to premature failure of the structure, for example byfatigue failure of the stent struts. Failure of the structure may resultin injury to the interstitial tissue and/or occlusion of theinterconnecting passage, which could lead to significant complicationsor complete failure of the therapy.

FIG. 8 illustrates a device or implant or prosthetic 100 for providingor maintaining fluid flow through at least one passage. The device 100includes a first or proximal end portion 102, a second or distal endportion 104, and an intermediate portion 106 between the proximal endportion 102 and the distal end portion 104. The device includes a boreor lumen 110 for passage of fluid through the device 100. The device100, for example at least the intermediate portion 106 of the device100, includes a flexible polymer tube 108. The flexible polymer tube 108may at least partially define the lumen 110.

The device 100 includes a support structure (e.g., at least one stent)including a mesh 112 and a mesh 114. In some embodiments, at least aportion of the mesh 112 is embedded in the outside wall of the tube 108proximate to the proximal end portion 102 of the device 100. In someembodiments, at least a portion of the mesh 114, for example a wire or astrut, is embedded in the outside wall of the tube 108 proximate to thedistal end portion 104 of the device 100. The meshes 112, 114 mayinclude biocompatible metal such as stainless steel and/or shape memorymaterial such as nitinol or chromium cobalt.

The wire meshes 112, 114 can stiffen the end portions 102, 104,respectively. In some embodiments in which the intermediate portion 106does not include a mesh, the intermediate portion 106 may be relativelyflexible in comparison to the end portions 102, 104, and/or the endportions 102, 104 may have a relatively high radial stiffness.

In some embodiments, the end portions 102, 104 of the device 100 arediametrically expandable. For example, the wire meshes 112, 114 may havea smaller diameter after formation or manufacture than the passages, forexample blood vessels, into which the device 100 will be deployed. Whenthe device 100 is in position in the passages, the end portions 102, 104can be expanded or deformed outwardly so that the respective diametersof the end portions 102, 104 increase, for example to abut the interiorsidewalls of the passages. The end portions 102, 104 are configured tomaintain the expanded diameter indefinitely, for example by plasticdeformation of the material (e.g., wires, struts) of the meshes 112, 114and/or by provision of a locking mechanism arranged to mechanically lockthe meshes 112, 114 in the expanded position. The intermediate portion106 of the device 100 may be diametrically expandable, for example byway of plastic deformation of the tube 108.

FIG. 9 shows the device 100 of FIG. 8 deployed to provide a fluid flowpath between a first passage 116 and a second passage 118. The passages116, 118 may include coronary blood vessels, for example a coronaryartery 116 and a coronary vein 118, or vice versa. The passages 116, 118may include peripheral blood vessels (e.g., blood vessels in limbs), forexample a femoral or other peripheral artery 116 and a femoral or otherperipheral vein 118, or vice versa. The end portions 102, 104 and theintermediate portion 106 of the device 100 have been expanded to meetwith and push against the inner walls of the passages 116, 118. Thedistal end portion 104 of the device 100 is located within the secondpassage 118, and the proximal end portion 102 of the device 100 islocated within the first passage 116. The intermediate portion 106extends through an opening or interconnecting passage 130 surgicallyformed between the passages 116, 118.

The expanded end portions 102, 104 of the device 100 are resilient, andimpart an outward radial force on the inner walls of the passages 116,118. By virtue of the radial stiffness of the end portions 102, 104 ofthe device 100, the end portions 102, 104 are held or anchored in placewithin the respective passages 116, 118. Slippage of the device 100within the passages 116, 118 is thereby prevented or reduced. In thisway, the end portions 102, 104 of the device 100 can anchor or fix thedevice 100 in position, in use, while providing or maintaining fluidflow through the lumen 110 of the tube 108 (FIG. 8 ). In this way, thedevice 100 can act as a shunt between the first passage 116 and thesecond passage 118.

The intermediate portion 106 of the device 100 may be flexible, forexample allowing the intermediate portion 106 to form an ‘S’ shapeformed by the combination of the first passage 116, the second passage118, and the interconnecting passage 130 (FIG. 9 ). The flexibleintermediate portion 106 can allow the end portions 102, 104 of thedevice 100 to move with respect to one another in response to relativemovement of the passages 116, 118.

In embodiments in which the intermediate portion 106 does not include awire mesh but includes the flexible polymer material of the tube 108,the intermediate portion 106 may not be susceptible to damage due tomesh fatigue, for example upon cyclic or other stress imparted byrelative movement of the passages 116, 118.

The intermediate portion 106 of the device 100 has sufficient resilienceto maintain dilatation of the interconnecting passage 130, so that theinterconnecting passage 130 remains open to provide or maintain a pathfor blood flow from the artery 116 to the vein 118 by way of the lumen110 of the tube 108 (FIG. 8 ). Blood flow from the artery 116 to thevein 118, by way of the interconnecting passage 130, may thereby beprovided or maintained through the lumen 110 of the tube 108. The device100 at least partially supports the artery 116, the vein 118, and theinterconnecting passage 130 to provide a pathway for fluid communicationthrough the device 100.

The proximal end portion 102 and the distal end portion 104 of thedevice 100 are arranged so that, when the device 100 is deployed withthe distal end portion 104 in a vein 118 and the proximal end portion102 in an artery 116, for example as shown in FIG. 9 , the diameter ofthe expanded distal end portion 104 is sufficient to hold the distal endportion 104 within the vein 118, and the diameter of the expandedproximal end portion 102 is sufficient to hold the proximal end portion102 within the artery 116. The diameter of the proximal end portion 102may therefore differ from the diameter of the distal end portion 104. Byselecting appropriate diameters for the end portions 102, 104 and theintermediate portion 106, the device 100 can be tailored to a certainanatomy and/or the anatomy of an individual patient.

An example procedure for positioning the device 100 of FIG. 8 to providea shunt between an occluded artery 116 and a vein 118 (e.g., a coronaryartery 116 and a coronary vein 118, or a peripheral artery 116 and aperipheral vein 118) to achieve retroperfusion of arterial blood, forexample as shown in FIG. 9 , will now be described.

A catheter may be inserted into the patient's arterial system by way ofa small aperture cut, usually in the patient's groin area. The catheteris fed to the artery 116 and guided to a position upstream of the siteof the occlusion, for example at a site proximate and parallel orsubstantially parallel to a vein 118. A hollow needle is deployed fromthe catheter, through the wall of the artery 116, through theinterstitial tissue 132 that separates the artery 116 and vein 118, andthrough the wall of the vein 118. The path of the needle creates aninterconnecting passage or opening 130, which allows blood to flowbetween the artery 116 and the vein 118. Deployment of the needle may beguided by a transmitter (e.g., a directional ultrasound transmitter)coupled to a catheter in the artery 116 and a receiver (e.g., anomnidirectional ultrasound receiver) coupled to a catheter in the vein118, or vice versa, for example as described herein and in U.S. patentapplication Ser. No. 11/662,128. Other methods of forming the opening130 are also possible (e.g., with or without directional ultrasoundguidance, with other types of guidance such as described herein, fromvein to artery, etc.).

Before the needle is withdrawn from the passage 130, a guidewire (e.g.,as described with respect to the guidewire 14 of FIG. 3 ) is insertedthrough the hollow needle and into the vein 118. The needle is thenretracted, leaving the guidewire in place in the artery 116, the passage130, and the vein 118. The catheter carrying the needle can then bewithdrawn from the patient's body. The guidewire can be used to guidefurther catheters to the interconnecting passage 130 between the artery116 and the vein 118.

A catheter carrying the device 100 in a non-expanded state is advancedtowards the interconnecting passage 130, guided by the guidewire, forexample by a rapid exchange lumen or through the lumen 110. The cathetermay include, for example, a balloon catheter configured to expand atleast a portion of the device 100 and/or a catheter configured to allowself-expansion of at least a portion of the device 100. The distal endportion 104 of the device 100 is passed through the interconnectingpassage 130 and into the vein 118, leaving the proximal end portion 102in the artery 116. The intermediate portion 106 of the device 100 is atleast partially in the passage 130, and is at least partially within theartery 116 and the vein 118. The intermediate portion 106 flexes toadopt a curved or “S”-shaped formation, depending on the anatomy of thesite. Adoption of such curvature may conform the shape of anintermediate portion 106 extending through the interconnecting passage130, and optionally into at least one of the passages 116, 118, to theshape of at least the interconnecting passage 130.

The distal end portion 104 of the device 100 is expanded, for exampleupon inflation of a balloon or by self-expansion, so as to increase thediameter of the distal end portion 104 and anchor the distal end portion104 against the inner wall of the vein 118. The catheter may be adaptedto expand the intermediate portion 106 of the device 100, for example byinflation of a balloon, so that the interconnecting passage 130 can bewidened or dilated to obtain blood flow (e.g., sufficient blood flow)from the artery 116 to the vein 118. The proximal end portion 102 of thedevice 100 is expanded, for example upon inflation of a balloon or byself-expansion, so as to increase the diameter of the proximal endportion 102 and anchor the proximal end portion 102 against the innerwall of the artery 116.

After the end portions 102, 104 of the device 100 are expanded, forexample due to self-expansion and/or balloon expansion, and with orwithout improving expansion after deployment, the catheter and theguidewire are withdrawn from the patient's body. In this way, the device100 is anchored or fixed in position within the vein 118, the artery116, and the interconnecting passage 130 as shown in FIG. 9 . Inembodiments in which the device 100 comprises a stent-graft, the graft,which can form a fluid-tight passage between the artery 116 and the vein118, can inhibit or prevent blood from flowing antegrade in the vein 118because such passageway is blocked, which can be in addition to orinstead of a blocking agent in the vein 118.

The catheter may be adapted to selectively expand the proximal endportion 102, the distal end portion 104, and/or the intermediate portion106 of the device 100 individually or in combination, for example by theprovision of two or more separately inflatable balloons or balloonportions, a single balloon configured to expand all of the portions ofthe device 100 simultaneously, or a single balloon configured to expandone or more selected portions of the device 100. For example, the endportions 102, 104 may be self-expanding, and the intermediate portion106 may be expanded by a balloon to dilate the passage 130. In someembodiments including balloon expansion, all or selected parts of thedevice 100 may be expanded, for example, simultaneously by a balloonacross the entire length of the device 100 or by a plurality of balloonslongitudinally spaced to selectively inflate selected parts of thedevice 100, and/or sequentially by a balloon or plurality of balloons.In some embodiments including at least partial self-expansion, all orselected parts of the device 100 may be expanded, for example, byproximal retraction of a sheath over or around the device 100, which canlead to deployment of the device 100 from distal to proximal as thesheath is proximally retracted. Deployment of the device 100 proximal todistal and deployment of the device 100 intermediate first then the endsare also possible. In some embodiments, for example embodiments in whichthe device 100 is at least partially conical or tapered, a conical ortapered balloon may be used to at least partially expand the device 100.In certain such embodiments, a portion of the balloon proximate to thevein 118 may have a larger diameter than a portion of the balloonproximate to the artery 116, for example such that the device 100 canadapt to changing vein diameters due to any increase in pressure orblood flow in the vein 118.

Other steps may be included in the procedure. For example, before thedevice 100 is deployed, a balloon catheter may be guided to theinterconnecting passage 130 and positioned so that an inflatable balloonportion of the catheter lies in the interconnecting passage 130. Uponinflation of the balloon, the balloon pushes against the walls of theinterconnecting passage 130 to widen or dilate the interconnectingpassage 130 to ease subsequent insertion of the device 100.

FIG. 10 illustrates another device 134 for providing fluid flow throughat least one passage. The device 134 includes a mesh 136 and a polymertube 108. The mesh 136 is shown as being on the outside of the polymertube 108, but as described herein could also or alternatively be on aninside of the polymer tube and/or within the polymer tube 108. Asdescribed with respect to the device 100, the device 134 includes aproximal end portion 102, a distal end portion 104, and an intermediateportion 106. In the embodiment illustrated in FIG. 10 , the mesh 136extends along the entire length of the device 134, including along theintermediate portion 106.

In some embodiments, the spacing of filaments or struts of the mesh 136varies along the length of the device 134. For example, winding densityof a woven or layered filamentary mesh may be varied and/or a windowsize pattern of a cut mesh may be varied.

In some embodiments, the spacing may be relatively small in the proximalend portion 102 and the distal end portions 104, and the spacing may berelatively large in the intermediate portion 106. In other words, thedensity or window size of the mesh 136 may be relatively low in theintermediate portion 106, and the density or window size of the mesh 136may be relatively high in the end portions 102, 104. In certain suchembodiments, the intermediate portion 106 may be flexible in comparisonto the end portions 102, 104. The relatively rigid end portions 102, 104may engage and anchor in passages. Although the mesh 136 in theintermediate portion 106 may be subject to stress such as cyclic stress,in use, the relatively high flexibility of the intermediate portion 106due to the low density or window size allows the impact of the stress tobe low because the intermediate portion 106 can flex in response to thestress. The risk of fatigue failure of the device 134, and particularlythe filaments or struts 138 of the mesh 136, may therefore be reduced incomparison to a device having uniform flexibility along its entirelength.

In some embodiments, the spacing may be relatively large in the proximalend portion 102 and the distal end portions 104, and the spacing may berelatively small in the intermediate portion 106. In other words, thedensity of the mesh 136 may be relatively high (or the window size ofthe mesh 136 may be relatively low) in the intermediate portion 106, andthe density of the mesh 136 may be relatively low (or the window size ofthe mesh 136 may be relatively high) in the end portions 102, 104. Incertain such embodiments, the intermediate portion 106 may have radialstrength sufficient to inhibit or prevent collapse of the passage 130,yet still, flexible enough to flex in response to stress such as cyclicstress. The end portions 102, 104 may engage and anchor in passages.

FIG. 11 illustrates another device or implant or prosthetic 140 forproviding fluid flow through at least one passage. As described withrespect to the device 100, the device 140 includes a proximal endportion 102, a distal end portion 104, and an intermediate portion 106.The device 140 includes a polymer tube 108 and a support structureincluding a first mesh 142 and a second mesh 144. The first mesh 142extends from the proximal end portion 102 toward (e.g., into) theintermediate portion 106 and optionally into the distal end portion 104.The second mesh 144 extends from the distal end portion 104 toward(e.g., into) the intermediate portion 106 and optionally into theproximal end portion 102. The meshes 142, 144 thereby overlap each otherat least in the intermediate portion 106. Both meshes 142, 144 may be onthe outside of the tube 108, on the inside of the tube 108, or embeddedwithin the tube 108, or one mesh may be on the outside of the tube 108,on the inside of the tube 108, or embedded within the tube 108 while theother mesh is differently on the outside of the tube 108, on the insideof the tube 108, or embedded within the tube 108 (e.g., one mesh insidethe tube 108 and one mesh outside the tube 108). The meshes 142, 144 maybe formed, for example, by winding wire in a lattice configurationaround or inside the polymer tube 108, by placing a cut tube around orinside the polymer tube 108, by being embedded in the polymer tube 108,combinations thereof, and the like.

In some embodiments, the density of the meshes 142, 144 is relativelyhigh (or the window size of the meshes 142, 144 is relatively low) intheir respective end portions 102, 104 and decreases in density (orincreases in window size) towards the intermediate portion 106. Thetotal winding density (e.g., the winding density of both meshes 142,144, taken together) may be lower in the intermediate portion 106 thanin the end portions 102, 104, or the total window size (e.g., the windowsize of both meshes 142, 144, taken together) may be higher in theintermediate portion 106 than in the end portions 102, 104. In certainsuch embodiments, the intermediate portion 106 is relatively flexible incomparison to the end portions 102, 104. In some embodiments, the meshes142, 144 do not extend into the intermediate portion, and absence of amesh could cause the intermediate portion 106 to be relatively flexiblein comparison to the end portions 102, 104. In some embodiments, aswindow size increases (e.g., longitudinally along a tapered portion ofthe device 140), the density decreases, the mesh coverage decreases,and/or the porosity increases because the width of the struts and/orfilaments remains substantially constant or constant or does notincrease in the same proportion as the window size, which could providea change in flexibility along a longitudinal length.

The first and second meshes 142, 144 may include different materials,which can allow optimization of the properties of each of the respectivedistal and proximal end portions 102, 104 of the device 140 for aparticular application of the device 140. For example, the second mesh144 at the distal end portion 104 of the device 140 may include arelatively flexible metallic alloy for ease of insertion through aninterconnecting passage between two blood vessels, while the first mesh142 at the proximal end portion 102 of the device 140 may include arelatively inelastic metallic alloy to provide a high degree ofresilience at the proximal end portion 104 to anchor the device 140firmly in position. The first and second meshes 142, 144 could includethe same material composition (e.g., both including nitinol) butdifferent wire diameters (gauge) or strut thicknesses.

FIG. 12 illustrates another device or implant or prosthetic 150 forproviding fluid flow through at least one passage. The device 150includes a support structure (e.g., stent) 152 and a graft 154. Asdescribed with respect to the device 100, the device 150 includes aproximal end portion 102, a distal end portion 104, and an intermediateportion 106. The proximal end portion 102 includes a cylindrical orsubstantially cylindrical portion and the distal end portion 104includes a cylindrical or substantially cylindrical portion. Thediameter of the proximal end portion 102 is smaller than the diameter ofthe distal end portion 104. In some embodiments, the diameter of theproximal end portion 102 is larger than the diameter of the distal endportion 104. The intermediate portion 106 has a tapered or frustoconicalshape between the proximal end portion 102 and the distal end portion104. The stent 152 may include filaments (e.g., woven, layered), a cuttube or sheet, and/or combinations thereof.

Parameters of the stent 152 may be uniform or substantially uniformacross a portion and/or across multiple portions, or may vary within aportion and/or across multiple portions. For example, the stent 152 atthe proximal end portion 102 may include a cut tube or sheet, the stent152 at the distal end portion 102 may include a cut tube or sheet, andthe stent 152 at the intermediate portion 106 may include filaments(e.g., woven or layered). Certain such embodiments may provide goodanchoring by the proximal end portion 102 and the distal end portion 104and good flexibility (e.g., adaptability to third passage sizes anddynamic stresses) of the intermediate portion 106.

The stent 152 may include different materials in different portions. Forexample, the stent 152 at the proximal end portion 102 may includechromium cobalt and/or tantalum, the stent 152 at the distal end portion104 may include nitinol, and the stent 152 at the intermediate portion106 may include nitinol. Certain such embodiments may provide goodanchoring and/or wall apposition by the device 150 in each deploymentareas (e.g., the proximal end portion 102 engaging sidewalls of anartery, the distal end portion 104 engaging sidewalls of a vein, and theintermediate portion 106 engaging sidewalls of the passage between theartery and the vein). In some embodiments in which the distal endportion 104 is self-expanding, the distal end portion 104 can adapt dueto changing vessel diameter (e.g., if vein diameter increases due to anincrease in pressure or blood flow), for example by furtherself-expanding.

Combinations of support structure materials and types are also possible.For example, the stent 152 at the proximal portion may include a cuttube or sheet including chromium cobalt and/or tantalum, the stent 152at the distal end portion 104 may include a cut tube or sheet includingnitinol, and the stent 152 at the intermediate portion 106 may includefilaments including nitinol.

In embodiments in which the stent 152 includes at least one portionincluding a cut tube or sheet, the cut pattern may be the same. Forexample, the cut pattern may be the same in the proximal end portion 102and the distal end portion 104, but proportional to the change indiameter. In some embodiments, the window size or strut density isuniform or substantially uniform within a portion 102, 104, 106, withintwo or more of the portions 102, 104, 106, and/or from one end of thestent 152 to the other end of the stent 152. In embodiments in which thestent 152 includes at least one portion including filaments, the windingmay be the same. For example, the winding may be the same in theproximal end portion 102 and the distal end portion 104, but changed dueto the change in diameter. In some embodiments, the winding density orporosity is uniform or substantially uniform within a portion 102, 104,106, within two or more of the portions 102, 104, 106, and/or from oneend of the stent 152 to the other end of the stent 152. In embodimentsin which the stent 152 includes at least one portion including a cuttube or sheet and at least one portion including filaments, the cutpattern and winding may be configured to result in a uniform orsubstantially uniform density. Non-uniformity is also possible, forexample as described herein.

The graft 154 may include materials and attachment to the stent 152 asdescribed with respect to the tube 108. The graft 154 generally forms afluid-tight passage for at least a portion of the device 150. Althoughillustrated as only being around the intermediate portion 106, the graft154 may extend the entire length of the device 150, or may partiallyoverlap into at least one of the cylindrical end portions 102, 104.

FIG. 13 illustrates another device 160 for providing fluid flow throughat least one passage. The device 160 includes a support structure (e.g.,stent) and a graft 164. As described with respect to the device 100, thedevice 160 includes a proximal end portion 102, a distal end portion104, and an intermediate portion 106. The proximal end portion 102includes a tapered or frustoconical portion and the distal end portion104 includes a tapered or frustoconical portion. The diameter of theproximal end of the proximal end portion 102 is smaller than thediameter of the distal end of the distal end portion 104. In someembodiments, the diameter of the proximal end of the proximal endportion 102 is larger than the diameter of the distal end of the distalend portion 104. The intermediate portion 106 has a tapered orfrustoconical shape between the proximal end portion 102 and the distalend portion 104. In some embodiments, the angle of inclination of theportions 102, 104, 106 is the same or substantially the same (e.g., asillustrated in FIG. 13 ). In some embodiments, the angle of inclinationof at least one portion is sharper or narrower than at least one otherportion. The frustoconical proximal end portion 102 and distal endportion 104 may allow better anchoring in a body passage, for examplebecause arteries tend to taper with distance from the heart and veinstend to taper with distance towards the heart, and the end portions 102,104 can be configured to at least partially correspond to suchanatomical taper.

FIG. 12 illustrates a device 150 comprising a first cylindrical orstraight portion, a conical or tapered portion, and second cylindricalor straight portion. FIG. 13 illustrates a device 160 comprising one ormore conical or tapered sections (e.g., the entire device 160 beingconical or tapered or comprising a plurality of conical or taperedsections). In some embodiments, combinations of the devices 150, 160 arepossible. For example, a device may comprise a cylindrical or straightportion and a conical or tapered portion for the remainder of thedevice. In certain such embodiments, the device may have a lengthbetween about 1 cm and about 10 cm (e.g., about 5 cm), which includes acylindrical or straight portion having a diameter between about 1 mm andabout 5 mm (e.g., about 3 mm) and a length between about 0.5 cm andabout 4 cm (e.g., about 2 cm) and a conical or tapered portion having adiameter that increases from the diameter of the cylindrical or straightportion to a diameter between about 3 mm and about 10 mm (e.g., about 5mm) and a length between about 1 cm and about 6 cm (e.g., about 3 cm).Such a device may be devoid of another cylindrical or conical portionthereafter.

As described above with respect to the support structure 152, thesupport structure 162 may include filaments (e.g., woven, layered), acut tube or sheet, the same materials, different materials, andcombinations thereof.

The graft 164 may include materials and attachment to the stent 162 asdescribed with respect to the tube 108. The graft 164 generally forms afluid-tight passage for at least a portion of the device 160. Althoughillustrated as only being around the intermediate portion 106, the graft164 may extend the entire length of the device 160, or may partiallyoverlap into at least one of the frustoconical end portions 102, 104.

In some embodiments, a combination of the device 150 and the device 160are possible. For example, the proximal end portion 102 can becylindrical or substantially cylindrical (e.g., as in the device 150),the distal end portion 104 can be tapered or frustoconical (e.g., as inthe device 160), with the proximal end portion 102 having a largerdiameter than the distal end of the distal end portion 104. For anotherexample, the proximal end portion 102 can be tapered or frustoconical(e.g., as in the device 160), the distal end portion 104 can becylindrical or substantially cylindrical (e.g., as in the device 150),with the proximal end of the proximal end portion 102 having a largerdiameter than the distal end portion 104. In each example, theintermediate portion 106 can have a tapered or frustoconical shapebetween the proximal end portion 102 and the distal end portion 104.

An example deployment device for the implantable devices describedherein is described in U.S. patent application Ser. No. 12/545,982,filed Aug. 24, 2009, and U.S. patent application Ser. No. 13/486,249,filed Jun. 1, 2012, the entire contents of each of which is herebyincorporated by reference. The device generally includes a handle at theproximal end with a trigger actuatable by a user and a combination oftubular member at the distal end configured to be pushed and/or pulledupon actuation of the trigger to release the device. Other deliverydevices are also possible. The delivery device may include a portionslidable over a guidewire (e.g., a guidewire that has been navigatedbetween the artery and the vein via a tissue traversing needle) and/ormay be trackable through a lumen of a catheter.

Although certain embodiments and examples are shown or described hereinin detail, various combinations, sub-combinations, modifications,variations, substitutions, and omissions of the specific features andaspects of those embodiments are possible, some of which will now bedescribed by way of example only.

The device, for example a stent of the device, a mesh of the device, asupport structure of the device, etc., may be self-expanding. Forexample, a mesh may include a shape-memory material, such as nitinol,which is capable of returning to a pre-set shape after undergoingdeformation. In some embodiments, the stent may be manufactured to ashape that is desired in the expanded configuration, and is compressibleto fit inside a sleeve for transport on a catheter to a vascular site.To deploy and expand the stent, the sleeve is drawn back from the stentto allow the shape memory material to return to the pre-set shape, whichcan anchor the stent in the passages, and which may dilate the passagesif the stent has sufficient radial strength. The use of a ballooncatheter is not required to expand a fully self-expanding stent, but maybe used, for example, to improve or optimize the deployment.

A device may include one or more self-expanding portions, and one ormore portions which are expandable by deformation, for example using aballoon catheter. For example, in the embodiment shown in FIG. 11 , thefirst mesh 142 may include stainless steel expandable by a ballooncatheter, and the second mesh 144 may include nitinol for self-expansionupon deployment.

With respect to any of the embodiments described herein, the polymertube 108, including the grafts 154, 164, may include any suitablecompliant or flexible polymer, such as PTFE, silicone, polyethyleneterephthalate (PET), polyurethane such as polycarbonate aromaticbiodurable thermoplastic polyurethane elastomer (e.g., ChronoFlex C® 80Aand 55D medical grade, available from AdvanSource Biomaterials ofWilmington, Mass.), combinations thereof, and the like. The polymer tube108 may include biodegradable, bioabsorbable, or biocompatible polymer(e.g., polylactic acid (PLA), polyglycolic acid (PGA),polyglycolic-lactic acid (PLGA), polycaprolactone (PCL),polyorthoesters, polyanhydrides, combinations thereof, etc. The polymermay be in tube form before interaction with a support structure (e.g.,stent), or may be formed on, in, and/or around a support structure(e.g., stent). For example, the polymer may include spun fibers, adip-coating, combinations thereof, and the like. In some embodiments,for example when the device is to be deployed within a single bloodvessel, the device may omit the tube. In certain such embodiments, theintermediate portion of the stent may include a mesh with a low windingdensity or high window size, while the end portions of the stent includea mesh with a higher winding density or lower window size, the meshbeing generally tubular to define a pathway for fluid flow through thecenter of the mesh. In some embodiments, the polymer tube 108 includes alip (e.g., comprising the same or different material), which can helpform a fluid-tight seal between the polymer tube 108 and the bodypassages. The seal may be angled, for example to account for angledpositioning of the polymer tube 108 between body passages. In someembodiments, the polymer tube 108 may extend longitudinally beyond thesupport structure in at least one direction, and the part extendingbeyond is not supported by the support structure.

The mesh may include any suitable material, such as nickel, titanium,chromium, cobalt, tantalum, platinum, tungsten, iron, manganese,molybdenum, combinations thereof (e.g., nitinol, chromium cobalt,stainless steel), and the like. The mesh may include biodegradable,bioabsorbable, or biocompatible polymer (e.g., polylactic acid (PLA),polyglycolic acid (PGA), polyglycolic-lactic acid (PLGA),polycaprolactone (PCL), polyorthoesters, polyanhydrides, combinationsthereof, etc.) and/or glass, and may lack metal. Different materials maybe used for portions of the mesh or within the same mesh, for example aspreviously described with reference to FIG. 11 . For example, the mesh114 at the distal end portion 104 and the mesh 112 at the proximal endportion 102 of the device 100 may include different materials. Foranother example, the mesh 112, and/or the mesh 114, may include ametallic alloy (e.g., comprising cobalt, chromium, nickel, titanium,combinations thereof, and the like) in combination with a different typeof metallic alloy (e.g., a shape memory alloy in combination with anon-shape memory alloy, a first shape memory alloy in combination with asecond shape memory alloy different than the first shape memory alloy, aclad material (e.g., comprising a core including a radiopaque materialsuch as titanium, tantalum, rhenium, bismuth, silver, gold, platinum,iridium, tungsten, etc.)) and/or a non-metallic material such as apolymer (e.g., polyester fiber), carbon, and/or bioabsorbable glassfiber. In some embodiments, at least one mesh 112, 114 comprises nitinoland stainless steel. The nitinol may allow some self-expansion (e.g.,partial and/or full self-expansion), and the mesh could then be furtherexpanded, for example using a balloon.

Although generally illustrated in FIGS. 8, 10, and 11 as a wovenfilament mesh, any other structure that can provide the desired degreeof resilience may be used. For example, layers of filaments wound inopposite directions may be fused at the filament ends to provide anexpandable structure. For another example, a metal sheet may be cut(e.g., laser cut, chemically etched, plasma cut, etc.) to formperforations and then heat set in a tubular formation or a metal tube(e.g., hypotube) may be cut (e.g., laser cut, chemically etched, plasmacut, etc.) to form perforations. A cut tube (including a cut sheetrolled into a tube) may be heat set to impart an expanded configuration.

Filaments or wires or ribbons that may be woven or braided, or layeredor otherwise arranged, are generally elongate and have a circular, oval,square, rectangular, etc. transverse cross-section. Example non-wovenfilaments can include a first layer of filaments wound in a firstdirection and a second layer of filaments wound in a second direction,at least some of the filament ends being coupled together (e.g., bybeing coupled to an expandable ring). Example braid patterns includeone-over-one-under-one, a one-over-two-under-two, atwo-over-two-under-two, and/or combinations thereof, although otherbraid patterns are also possible. At filament crossings, filaments maybe helically wrapped, cross in sliding relation, and/or combinationsthereof. Filaments may be loose (e.g., held together by the weave)and/or include welds, coupling elements such as sleeves, and/orcombinations thereof. Ends of filaments can be bent back, crimped (e.g.,end crimp with a radiopaque material such as titanium, tantalum,rhenium, bismuth, silver, gold, platinum, iridium, tungsten, etc. thatcan also act as a radiopaque marker), twisted, ball welded, coupled to aring, combinations thereof, and the like. Weave ends may includefilament ends and/or bent-back filaments, and may include open cells,fixed or unfixed filaments, welds, adhesives, or other means of fusion,radiopaque markers, combinations thereof, and the like. Parameters ofthe filaments may be uniform or substantially uniform across a portionand/or across multiple portions, or may vary within a portion and/oracross multiple portions. For example, the proximal end portion 102 mayinclude a first parameter and the distal end portion 104 may include asecond parameter different than the first braid pattern. For anotherexample, the proximal end portion 102 and the distal end portion 104 mayeach include a first parameter and the intermediate portion 106 mayinclude a second parameter different than the parameter. For yet anotherexample, at least one of the proximal end portion 102, the distal endportion 104, and the intermediate portion 106 may include both a firstparameter and a second parameter different than the first parameter.Filament parameters may include, for example, filament type, filamentthickness, filament material, quantity of filaments, weave pattern,layering, wind direction, pitch, angle, crossing type, filament couplingor lack thereof, filament end treatment, weave end treatment, layeringend treatment, quantity of layers, presence or absence of welds,radiopacity, braid pattern, density, porosity, filament angle, braiddiameter, winding diameter, and shape setting.

Tubes or sheets may be cut to form strut or cell patterns, struts beingthe parts of the tube or sheet left after cutting and cells orperforations or windows being the parts cut away. A tube (e.g.,hypotube) may be cut directly, or a sheet may be cut and then rolledinto a tube. The tube or sheet may be shape set before or after cutting.The tube or sheet may be welded or otherwise coupled to itself, toanother tube or sheet, to filaments, to a graft material, etc. Cuttingmay be by laser, chemical etchant, plasma, combinations thereof, and thelike. Example cut patterns include helical spiral, weave-like, coil,individual rings, sequential rings, open cell, closed cell, combinationsthereof, and the like. In embodiments including sequential rings, therings may be coupled using flex connectors, non-flex connectors, and/orcombinations thereof. In embodiments including sequential rings, therings connectors (e.g., flex, non-flex, and/or combinations thereof) mayintersect ring peaks, ring valleys, intermediate portions of struts,and/or combinations thereof (e.g., peak-peak, valley-valley, mid-mid,peak-valley, peak-mid, valley-mid, valley-peak, mid-peak, mid-valley).The tube or sheet or sections thereof may be ground and/or polishedbefore or after cutting. Interior ridges may be formed, for example toassist with fluid flow. Parameters of the cut tube or sheet may beuniform or substantially uniform across a portion and/or across multipleportions, or may vary within a portion and/or across multiple portions.For example, the proximal end portion 102 may include a first parameterand the distal end portion 104 may include a second parameter differentthan the first parameter. For another example, the proximal end portion102 and the distal end portion 104 may each include a first parameterand the intermediate portion 106 may include a second parameterdifferent than the parameter. For yet another example, at least one ofthe proximal end portion 102, the distal end portion 104, and theintermediate portion 106 may include both a first parameter and a secondparameter different than the first parameter. Cut tube or sheetparameters may include, for example, radial strut thickness,circumferential strut width, strut shape, cell shape, cut pattern, cuttype, material, density, porosity, tube diameter, and shape setting.

In some embodiments, the perforations may provide the mesh with arelatively flexible intermediate portion and relatively stiff endportions. The supporting structure may instead be an open-cell foamdisposed within the tube.

Filaments of a stent, stent-graft, or a portion thereof, and/or strutsof a cut stent, stent-graft, or a portion thereof, may be surfacemodified, for example to carry medications such as thrombosis modifiers,fluid flow modifiers, antibiotics, etc. Filaments of a stent,stent-graft, or a portion thereof, and/or struts of a cut stent,stent-graft, or a portion thereof, may be at least partially coveredwith a coating including medications such as thrombosis modifiers, fluidflow modifiers, antibiotics, etc., for example embedded within a polymerlayer or a series of polymer layers, which may be the same as ordifferent than the polymer tube 108.

Thickness (e.g., diameter) of filaments of a stent, stent-graft, or aportion thereof, and/or struts of a cut stent, stent-graft, or a portionthereof, may be between about 0.0005 inches and about 0.02 inches,between about 0.0005 inches and about 0.015 inches, between about 0.0005inches and about 0.01 inches, between about 0.0005 inches and about0.008 inches, between about 0.0005 inches and about 0.007 inches,between about 0.0005 inches and about 0.006 inches, between about 0.0005inches and about 0.005 inches, between about 0.0005 inches and about0.004 inches, between about 0.0005 inches and about 0.003 inches,between about 0.0005 inches and about 0.002 inches, between about 0.0005inches and about 0.001 inches, between about 0.001 inches and about 0.02inches, between about 0.001 inches and about 0.015 inches, between about0.001 inches and about 0.01 inches, between about 0.001 inches and about0.008 inches, between about 0.001 inches and about 0.007 inches, betweenabout 0.001 inches and about 0.006 inches, between about 0.001 inchesand about 0.005 inches, between about 0.001 inches and about 0.004inches, between about 0.001 inches and about 0.003 inches, between about0.001 inches and about 0.002 inches, between about 0.002 inches andabout 0.02 inches, between about 0.002 inches and about 0.015 inches,between about 0.002 inches and about 0.01 inches, between about 0.002inches and about 0.008 inches, between about 0.002 inches and about0.007 inches, between about 0.002 inches and about 0.006 inches, betweenabout 0.002 inches and about 0.005 inches, between about 0.002 inchesand about 0.004 inches, between about 0.002 inches and about 0.003inches, between about 0.003 inches and about 0.02 inches, between about0.003 inches and about 0.015 inches, between about 0.003 inches andabout 0.01 inches, between about 0.003 inches and about 0.008 inches,between about 0.003 inches and about 0.007 inches, between about 0.003inches and about 0.006 inches, between about 0.003 inches and about0.005 inches, between about 0.003 inches and about 0.004 inches, betweenabout 0.004 inches and about 0.02 inches, between about 0.004 inches andabout 0.015 inches, between about 0.004 inches and about 0.01 inches,between about 0.004 inches and about 0.008 inches, between about 0.004inches and about 0.007 inches, between about 0.004 inches and about0.006 inches, between about 0.004 inches and about 0.005 inches, betweenabout 0.005 inches and about 0.02 inches, between about 0.005 inches andabout 0.015 inches, between about 0.005 inches and about 0.01 inches,between about 0.005 inches and about 0.008 inches, between about 0.005inches and about 0.007 inches, between about 0.005 inches and about0.006 inches, between about 0.006 inches and about 0.02 inches, betweenabout 0.006 inches and about 0.015 inches, between about 0.006 inchesand about 0.01 inches, between about 0.006 inches and about 0.008inches, between about 0.006 inches and about 0.007 inches, between about0.007 inches and about 0.02 inches, between about 0.007 inches and about0.015 inches, between about 0.007 inches and about 0.01 inches, betweenabout 0.007 inches and about 0.008 inches, between about 0.008 inchesand about 0.02 inches, between about 0.008 inches and about 0.015inches, between about 0.008 inches and about 0.01 inches, between about0.01 inches and about 0.02 inches, between about 0.01 inches and about0.015 inches, or between about 0.015 inches and about 0.02 inches. Otherthicknesses are also possible, including thicknesses greater than orless than the identified thicknesses. Filaments and/or struts comprisingcertain materials (e.g., biodegradable material, materials with lessrestoring force, etc.) may be thicker than the identified thicknesses.

Thicknesses of filaments and/or struts may be based, for example, on atleast one of device or device portion size (e.g., diameter and/orlength), porosity, radial strength, material, quantity of filamentsand/or struts, cut pattern, weave pattern, layering pattern, and thelike. For example, larger filament and/or strut thicknesses (e.g.,greater than about 0.006 inches) may be useful for large devices ordevice portions used to treat large vessels such as coronary vessels,mid-sized filament and/or strut thicknesses (e.g., between about 0.003inches and about 0.006 inches) may be useful for mid-sized used to treatmid-sized vessels such as peripheral vessels, and small filament and/orstrut thicknesses (e.g., less than about 0.003 inches) may be useful forsmall devices or device portions used to treat small vessels such asveins and neurological vessels.

The internal or external diameter of a stent, a stent-graft, or a firstend portion, second end portion, intermediate portion, or subportionthereof, for example taking into account filament or strut thickness,may be between about 1 mm and about 12 mm, between about 1 mm and about10 mm, between about 1 mm and about 8 mm, between about 1 mm and about 6mm, between about 1 mm and about 4 mm, between about 1 mm and about 2mm, between about 2 mm and about 12 mm, between about 2 mm and about 10mm, between about 2 mm and about 8 mm, between about 2 mm and about 6mm, between about 2 mm and about 4 mm, between about 4 mm and about 12mm, between about 4 mm and about 10 mm, between about 4 mm and about 8mm, between about 4 mm and about 6 mm, between about 6 mm and about 12mm, between about 6 mm and about 10 mm, between about 6 mm and about 8mm, between about 8 mm and about 12 mm, between about 8 mm and about 10mm, or between about 10 mm and about 12 mm. Certain such diameters maybe suitable for treating, for example, coronary vessels. The internal orexternal diameter of a stent, a stent-graft, or a portion thereof, forexample taking into account filament or strut thickness, may be betweenabout 1 mm and about 10 mm, between about 1 mm and about 8 mm, betweenabout 1 mm and about 6 mm, between about 1 mm and about 4 mm, betweenabout 1 mm and about 2 mm, between about 2 mm and about 10 mm, betweenabout 2 mm and about 8 mm, between about 2 mm and about 6 mm, betweenabout 2 mm and about 4 mm, between about 4 mm and about 10 mm, betweenabout 4 mm and about 8 mm, between about 4 mm and about 6 mm, betweenabout 6 mm and about 10 mm, between about 6 mm and about 8 mm, orbetween about 8 mm and about 10 mm. Certain such diameters may besuitable for treating, for example, veins. The internal or externaldiameter of a stent, a stent-graft, or a portion thereof, for exampletaking into account filament or strut thickness, may be between about 6mm and about 25 mm, between about 6 mm and about 20 mm, between about 6mm and about 15 mm, between about 6 mm and about 12 mm, between about 6mm and about 9 mm, between about 9 mm and about 25 mm, between about 9mm and about 20 mm, between about 9 mm and about 15 mm, between about 9mm and about 12 mm, between about 12 mm and about 25 mm, between about12 mm and about 20 mm, between about 12 mm and about 15 mm, betweenabout 15 mm and about 25 mm, between about 15 mm and about 20 mm, orbetween about 20 mm and about 25 mm. Certain such diameters may besuitable for treating, for example, peripheral vessels. The internal orexternal diameter of a stent, a stent-graft, or a portion thereof, forexample taking into account filament or strut thickness, may be betweenabout 20 mm and about 50 mm, between about 20 mm and about 40 mm,between about 20 mm and about 35 mm, between about 20 mm and about 30mm, between about 30 mm and about 50 mm, between about 30 mm and about40 mm, between about 30 mm and about 35 mm, between about 35 mm andabout 50 mm, between about 35 mm and about 40 mm, or between about 40 mmand about 50 mm. Certain such diameters may be suitable for treating,for example, aortic vessels. Other diameters are also possible,including diameters greater than or less than the identified diameters.The diameter of the device may refer to the diameter of the first endportion, the second end portion, or the intermediate portion, each ofwhich may be in expanded or unexpanded form. The diameter of the devicemay refer to the average diameter of the device when all of the portionsof the device are in either expanded or unexpanded form.

The length of a stent, a stent-graft, or a first end portion, second endportion, intermediate portion, or subportion thereof may be betweenabout 5 mm and about 150 mm, between about 5 mm and about 110 mm,between about 5 mm and about 70 mm, between about 5 mm and about 50 mm,between about 5 mm and about 25 mm, between about 5 mm and about 20 mm,between about 5 mm and about 10 mm, between about 10 mm and about 150mm, between about 10 mm and about 110 mm, between about 10 mm and about70 mm, between about 10 mm and about 50 mm, between about 10 mm andabout 25 mm, between about 10 mm and about 20 mm, between about 20 mmand about 150 mm, between about 20 mm and about 110 mm, between about 20mm and about 70 mm, between about 20 mm and about 50 mm, between about20 mm and about 25 mm, between about 25 mm and about 150 mm, betweenabout 25 mm and about 110 mm, between about 25 mm and about 70 mm,between about 25 mm and about 50 mm, between about 50 mm and about 150mm, between about 50 mm and about 110 mm, between about 50 mm and about70 mm, between about 70 mm and about 150 mm, between about 70 mm andabout 110 mm, or between about 110 mm and about 150 mm. Other lengthsare also possible, including lengths greater than or less than theidentified lengths.

The porosity of a stent, a stent-graft, or a first end portion, secondend portion, intermediate portion, or subportion thereof may be betweenabout 5% and about 95%, between about 5% and about 50%, between about 5%and about 25%, between about 5% and about 10%, between about 10% andabout 50%, between about 10% and about 25%, between about 25% and about50%, between about 50% and about 95%, between about 50% and about 75%,between about 50% and about 60%, between about 60% and about 95%,between about 75% and about 90%, between about 60% and about 75%, andcombinations thereof. The density of a stent may be inverse to theporosity of that stent. The porosity of a portion of a stent covered bya graft may be about 0%. The porosity may vary by objectives for certainportions of the stent. For example, the intermediate portion may have alow porosity to increase fluid flow through the device, while endportions may have lower porosity to increase flexibility and wallapposition.

FIG. 25A is a schematic side elevational view of yet another exampleembodiment of a prosthesis 500. The prosthesis or stent or device 500includes and/or consist essentially of a plurality of filaments 502woven together into a woven structure. The stent 500 may be devoid ofgraft material, as described in further detail below.

The filaments 502, which may also be described as wires, ribbons,strands, and the like, may be woven, braided, layered, or otherwisearranged in a crossing fashion. The filaments 502 are generally elongateand have a circular, oval, square, rectangular, etc. transversecross-section. Example non-woven filaments can include a first layer offilaments wound in a first direction and a second layer of filamentswound in a second direction, at least some of the filament ends beingcoupled together (e.g., by being coupled to an expandable ring). Exampleweave patterns include one-over-one-under-one (e.g., as shown in FIG.25A), a one-over-two-under-two, a two-over-two-under-two, and/orcombinations thereof, although other weave patterns are also possible.At crossings of the filaments 502, the filaments 502 may be helicallywrapped, cross in sliding relation, and/or combinations thereof. Thefilaments 502 may be loose (e.g., held together by the weave) and/orinclude welds, coupling elements such as sleeves, and/or combinationsthereof. Ends of filaments 502 can be bent back, crimped (e.g., endcrimp with a radiopaque material such as titanium, tantalum, rhenium,bismuth, silver, gold, platinum, iridium, tungsten, etc. that can alsoact as a radiopaque marker), twisted, ball welded, coupled to a ring,combinations thereof, and the like. Weave ends may include filament 502ends and/or bent-back filaments 502, and may include open cells, fixedor unfixed filaments 502, welds, adhesives, or other means of fusion,radiopaque markers, combinations thereof, and the like.

The stent 500 includes pores 504 or open, non-covered areas between thefilaments 502. The porosity of the stent 500 may be computed as theouter surface area of the pores 504 divided by the total outer surfacearea of the stent 500. The porosity may be affected by parameters suchas, for example, the number of filaments 502, the braid angle 506, thesize (e.g., diameter) of the filaments 502, and combinations thereof.

The porosity of the stent 500 may be less than about 50% (e.g., slightlymore covered than open), between about 0% (e.g., almost no open area)and about 50%, between about 0% and about 45%, between about 0% andabout 40%, between about 0% and about 35%, between about 0% and about30%, between about 0% and about 25%, between about 0% and about 20%,between about 0% and about 15%, between about 0% and about 10%, betweenabout 0% and about 5%, between about 5% and about 50%, between about 5%and about 45%, between about 5% and about 40%, between about 5% andabout 35%, between about 5% and about 30%, between about 5% and about25%, between about 5% and about 20%, between about 5% and about 15%,between about 5% and about 10%, between about 10% and about 50%, betweenabout 10% and about 45%, between about 10% and about 40%, between about10% and about 35%, between about 10% and about 30%, between about 10%and about 25%, between about 10% and about 20%, between about 10% andabout 15%, between about 15% and about 50%, between about 15% and about45%, between about 15% and about 40%, between about 15% and about 35%,between about 15% and about 35%, between about 15% and about 25%,between about 15% and about 20%, between about 20% and about 50%,between about 20% and about 45%, between about 20% and about 40%,between about 20% and about 35%, between about 20% and about 35%,between about 20% and about 25%, between about 25% and about 50%,between about 25% and about 45%, between about 25% and about 40%,between about 25% and about 35%, between about 25% and about 35%,between about 30% and about 50%, between about 30% and about 45%,between about 30% and about 40%, between about 30% and about 35%,between about 35% and about 50%, between about 35% and about 45%,between about 35% and about 40%, between about 40% and about 50%,between about 40% and about 45%, between about 45% and about 50%, andcombinations thereof.

In some embodiments in which the porosity is less than about 50%, bloodmay be unable to perfuse through the sidewalls of the stent 500 undernormal vascular pressures (e.g., a pressure drop across a vessel, apressure drop from an afferent vessel to an efferent vessel). In certainsuch embodiments, blood flowing into a proximal end of the stent 500 canbe directed through a lumen of the stent 500 to a distal end of thestent 500 without (e.g., substantially without, free of, substantiallyfree of) graft material, but still without loss or substantial loss ofblood through the sidewalls of the stent 500. By contrast, in certainso-called “flow diverting stents,” the porosity is specifically designedto be greater than about 50% in order to ensure perfusion to efferentvessels.

The density of the stent 500 may be inverse to the porosity (e.g., theouter surface area of the filaments 502 divided by the total outersurface area of the stent 500). The density of the stent 500 may be 100%minus the porosity values provided above.

The filaments 502 are at a braid angle 506 relative to an axisperpendicular to the longitudinal axis of the stent 500 (e.g., asillustrated by the example dashed line in FIG. 25A). The braid angle 506can range from just more than 90° to just under 180°. The braid angle506 can be acute or obtuse. In some embodiments, the braid angle 506 isbetween about 90° and about 180°, between about 120° and about 180°,between about 150° and about 180°, between about 160° and about 180°,between about 170° and about 180°, between about 160° and about 170°,between about 165° and about 175°, combinations thereof, and the like.In some embodiments, the closer the braid angle 506 is to 180°, thegreater the radial strength of the stent 500. Devices 500 with greaterradial strength may aid in keeping a fistula (e.g., formed as describedherein) open or patent. Other factors can also influence radial strengthsuch as filament 502 diameter, filament 502 material, number offilaments 502, etc.

The filaments 502 may all be the same or some of the filaments 502 mayhave a different parameter (e.g., material, dimensions, combinationsthereof, and the like). In some embodiments, some of the filaments 502comprise shape memory material (e.g., comprising nitinol) and others ofthe filaments 502 comprise another material (e.g., comprising aramidfiber (e.g., Kevlar®), Dacron®, biocompatible polymer, etc.). The shapememory material may provide the mechanical structure and the othermaterial may provide low porosity (e.g., by being thick in the dimensionof the sidewalls).

FIG. 25B is a schematic side elevational view of still yet anotherexample embodiment of a prosthesis 520. The prosthesis or stent ordevice 520 includes and/or consist essentially of a first plurality offilaments 522 woven together into a first woven structure and a secondplurality of filaments 524 woven together into a second woven structure.The stent 520 may be devoid of graft material, as described in furtherdetail herein. The first plurality of filaments 522 may be similar tothe filaments 502 of the stent 500 described with respect to FIG. 25A.In some embodiments, the filaments 522 may lack sufficient radial forceto keep a fistula open and/or to appose sidewalls of an artery and/or avein. In certain such embodiments, the filaments 524 may act as asupplemental support structure to provide the radial force. Thefilaments 524 may be radially outward of the filaments 522 (e.g., asillustrated in FIG. 25B), radially inward of the filaments 522, and/orintegrated with the filaments 522 (e.g., such that the first and secondwoven structures are not readily separable. The filaments 524 may be thesame or different material as the filaments 522, the same or differentthickness as the filaments 522, etc., and/or the filaments 524 may bebraided with the same or different parameters (e.g., braid angle) thanthe filaments 522, resulting in filaments 524 having greater radialforce. The filaments 524 may be coupled to the filaments 522 (e.g., in asingle deployable stent 520) or separately deployed. For example, if thefilaments 524 are deployed and then the filaments 522 are deployed, thefilaments 524 can prop open a fistula and allow the filaments 522 toexpand within the lumen created by the filaments 524 without substantialopposing force. For another example, if the filaments 522 are deployedand then the filaments 524 are deployed, the filaments 524 can act as anexpansion force on the portions of the filaments 522 in need of anexpansive force.

Although illustrated in FIG. 25B as comprising a second woven structure,the supplemental support structure may additionally or alternativelycomprise a helical coil, a cut hypotube, combinations thereof, and thelike. Determination of the porosity of the prosthesis 520 may beprimarily based on the porosity of the first woven structure such thatthe supplemental support structure may be designed primarily forproviding radial force (e.g., sufficient to keep a fistula open orpatent).

Although illustrated as being uniform or substantially uniform acrossthe length of the stent 500, parameters of the stent 500 and thefilaments 502 may vary across the stent 500, for example as describedwith respect to FIG. 25C. Uniformity may reduce manufacturing costs,reduce a demand for precise placement, and/or have other advantages.Non-uniformity may allow specialization or customization for specificproperties and/or functions along different lengths and/or have otheradvantages.

FIG. 25C is a schematic side elevational view of still another exampleembodiment of a prosthesis 540. The prosthesis or stent or device 540includes and/or consist essentially of a plurality of filaments 542woven together into a woven structure. The stent 540 may be devoid ofgraft material, as described in further detail herein. The stent 540comprises a first longitudinal section or segment or portion 544 and asecond longitudinal section or segment or portion 546. Parameters suchas porosity (e.g., as illustrated in FIG. 25B), braid angle, braid type,filament 542 parameters (e.g., diameter, material, etc.), existence of asupplemental support structure (e.g., the supplemental support structure544), stent diameter, stent shape (e.g., cylindrical, frustoconical),combinations thereof, and the like may be different between the firstlongitudinal section 544 and the second longitudinal section 546. Theporosity may vary by objectives for certain portions of the stent 540.For example, the first longitudinal section 544, which may be configuredfor placement in an artery and a fistula, may have low porosity (e.g.,less than about 50% as described with respect to the stent 500 of FIG.25A) to increase fluid flow through the stent 500, while the secondlongitudinal section, which may be configured for placement in a vein,may have higher porosity to increase flexibility and wall apposition.

In some embodiments, a stent comprises a first longitudinal sectioncomprising and/or consisting essentially of a low porosity weaveconfigured to divert flow from an artery into a fistula and nosupplemental support structure, a second longitudinal section comprisingand/or consisting essentially of a low porosity weave configured todivert blood flow through a fistula and comprising a supplementalsupport structure configured to prop open the fistula, and a thirdlongitudinal section comprising and/or consisting essentially of lowporosity weave configured to divert flow from a fistula into a vein. Incertain such embodiments, the first longitudinal section may beconfigured as the stent 500 of FIG. 25A and the third longitudinalsection may be configured as the stent 500 of FIG. 25A or as the stent540 of FIG. 25C.

The difference between the first longitudinal section 544 and the secondlongitudinal section 546 may be imparted during manufacturing (e.g., dueto braid parameters, shape setting, etc.) and/or in situ (e.g., duringand/or after deployment (e.g., by stent packing)).

Other variations between the first longitudinal section 544 and thesecond longitudinal section 546 (e.g., including laser-cut portions,additional longitudinal sections, etc.), for example as describedherein, are also possible. In some embodiments, a stent comprises afirst longitudinal section comprising and/or consisting essentially of alow porosity weave configured to divert flow from an artery into afistula, a second longitudinal section comprising and/or consistingessentially of a low porosity laser cut portion configured to be placedin a fistula, to divert blood through the fistula, and/or to prop openthe fistula, and a third longitudinal section comprising and/orconsisting essentially of low porosity weave configured to divert flowfrom a fistula into a vein. In certain such embodiments, the firstlongitudinal section may be configured as the stent 500 of FIG. 25A andthe third longitudinal section may be configured as the stent 500 ofFIG. 25A or as the stent 540 of FIG. 25C.

FIG. 27 schematically illustrates an example embodiment of a prosthesis720, which is described with respect to the anatomy in FIG. 27 infurther detail below. The prosthesis 720 comprises a first longitudinalsection 722, a second longitudinal section 724, and a third longitudinalsection 726 between the first longitudinal section 722 and the secondlongitudinal section 724. The porosity of the prosthesis 720 may allowthe fluid to flow substantially through the lumen of the prosthesis 720substantially without perfusing through the sidewalls, even whensubstantially lacking graft material, for example due to a low porositywoven structure.

In embodiments in which the prosthesis 720 is used in peripheralvasculature, the first longitudinal section 722 may be described as anarterial section, the second longitudinal section 724 may be describedas a venous section, and the third longitudinal section 726 may bedescribed as a transition section. The first longitudinal section 722 isconfigured to appose sidewalls of an artery 700 or another cavity. Forexample, for some peripheral arteries, the first longitudinal section722 may have an expanded diameter between about 2 mm and about 4 mm(e.g., about 3 mm). The second longitudinal section 724 is configured toappose sidewalls of a vein 702 or another cavity. For example, for someperipheral veins, the second longitudinal section 724 may have anexpanded diameter between about 5 mm and about 7 mm (e.g., about 6 mm).In some embodiments, rather than being substantially cylindrical asillustrated in FIG. 27 , the second longitudinal section 724 and thethird longitudinal section 726 may have a shape comprisingfrustoconical, tapering from the smaller diameter of the firstlongitudinal section 722 to a larger diameter.

The length of the prosthesis 720 may be configured or sized to anchorthe prosthesis 720 in the artery 700 and/or the vein 702 (e.g., enoughto inhibit or prevent longitudinal movement or migration of theprosthesis 720) and to span the interstitial tissue T between the artery700 and the vein 702. For example, for some peripheral arteries, thelength of the first longitudinal section 722 in the expanded or deployedstate may be between about 20 mm and about 40 mm (e.g., about 30 mm).For another example, for some peripheral veins, the length of the secondlongitudinal section 724 in the expanded or deployed state may bebetween about 10 mm and about 30 mm (e.g., about 20 mm). For yet anotherexample, for some peripheral vasculature, the length of the thirdlongitudinal section 726 in the expanded or deployed state may bebetween about 5 mm and about 15 mm (e.g., about 10 mm). The total lengthof the prosthesis 720 in the expanded or in a deployed state may bebetween about 30 mm and about 100 mm, between about 45 mm and about 75mm (e.g., about 60 mm). The interstitial tissue T is illustrated asbeing about 2 mm thick, although other dimensions are possible dependingon the specific anatomy of the deployment site. Other dimensions of theprosthesis 720, the first longitudinal section 722 and/or the secondlongitudinal section 724, for example as described herein, are alsopossible.

The third longitudinal section 726 comprises a frustoconical or taperedshape, expanding from the smaller diameter of the first longitudinalsection 722 to the second longitudinal section 724. Transition pointsbetween the longitudinal sections 722, 724, 726 may be distinct orindistinct. For example, the transition section may be said to include aportion of the first longitudinal section 722 and the third longitudinalsection 726, or the third longitudinal section 726 may be said toinclude a cylindrical portion having the same diameter as the firstlongitudinal section 722. The longitudinal sections 722, 724, 726 maydiffer in shape and dimensions as described above, and/or in other ways(e.g., materials, pattern, etc.). For example, one or more portions maybe cylindrical, frustoconical, etc., as illustrated in FIGS. 12, 13, and27 and described herein.

The first longitudinal section 722 and/or the third longitudinal section726 may comprise a relatively high radial force, for example configuredto keep a fistula patent, and the second longitudinal section 724 maycomprise a relatively low radial force. In some embodiments, the firstlongitudinal section 722 and/or the third longitudinal section 726comprise a balloon-expandable stent, a woven stent with a high braidangle, and/or the like. In some embodiments, the second longitudinalsection 724 comprises a self-expanding stent, a woven stent with a lowbraid angle, and/or the like. Combinations of laser-cut stents, wovenstents, different cut patterns, different weave patterns, and the likeare described in further detail herein. In some embodiments, thelongitudinal sections 722, 724, 726 may be integral or separate. Thesecond longitudinal section 724 may be relatively flexible, for examplecomprising relatively low radial force, which may help the secondlongitudinal section 724 flex with the anatomy during pulses of bloodflow.

In some embodiments, the second longitudinal section 724 and/or thethird longitudinal section 726 may comprise some graft material (e.g.,comprising silicone). The graft material may inhibit or prevent flowthrough sidewalls of the prosthesis 720 and/or may be used to carrymedicaments. For example, graft material may or may not occlude orsubstantially occlude the pores of the portions of the prosthesis 720depending on the purpose of the graft material.

The proximal and/or distal ends of the prosthesis 720 may be atraumatic,for example comprising an end treatment, low braid angle, small filamentdiameter, combinations thereof, and the like.

The radial strength or compression resistance of a stent, a stent-graft,or a first end portion, second end portion, intermediate portion, orsubportion thereof may be between about 0.1 N/mm and about 0.5 N/mm,between about 0.2 N/mm and about 0.5 N/mm, between about 0.3 N/mm andabout 0.5 N/mm, between about 0.1 N/mm and about 0.3 N/mm, between about0.1 N/mm and about 0.2 N/mm, between about 0.2 N/mm and about 0.5 N/mm,between about 0.2 N/mm and about 0.3 N/mm, or between about 0.3 N/mm andabout 0.5 N/mm.

The values of certain parameters of a stent, a stent-graft, or a firstend portion, second end portion, intermediate portion, or subportionthereof may be linked (e.g., proportional). For example, a ratio of athickness of a strut or filament to a diameter of a device portioncomprising that strut or filament may be between about 1:10 and about1:250, between about 1:25 and about 1:175, or between about 1:50 andabout 1:100. For another example, a ratio of a length of a device orportion thereof to a diameter of a device or a portion thereof may bebetween about 1:1 and about 50:1, between about 5:1 and about 25:1, orbetween about 10:1 and about 20:1.

Portions of the device may include radiopaque material. For example,filaments and/or struts a stent, a stent-graft, or a first end portion,second end portion, intermediate portion, or subportion thereof maycomprise (e.g., be at least partially made from) titanium, tantalum,rhenium, bismuth, silver, gold, platinum, iridium, tungsten,combinations thereof, and the like. For another example, filamentsand/or struts of a stent, stent-graft, or a portion thereof may comprise(e.g., be at least partially made from) a material having a densitygreater than about 9 grams per cubic centimeter. Separate radiopaquemarkers may be attached to certain parts of the device. For example,radiopaque markers can be added to the proximal end of the device orparts thereof (e.g., a proximal part of the intermediate portion, aproximal part of the distal portion), the distal end of the device orparts thereof (e.g., a distal part of the intermediate portion, a distalpart of the proximal portion), and/or other parts. A radiopaque markerbetween ends of a device may be useful, for example, to demarcatetransitions between materials, portions, etc. Radiopacity may varyacross the length of the device. For example, the proximal portion couldhave a first radiopacity (e.g., due to distal portion material and/orseparate markers) and the distal portion could have a second radiopacity(e.g., due to distal portion material and/or separate markers) differentthan the first radiopacity. Inflatable members such as balloons may befilled with radiopaque fluid. Inflatable members such as balloons maycomprise a radiopaque marker coupled and/or integrated thereto (e.g., onan outer surface of the inflatable member).

In some embodiments, the device includes a polymer tube, and nosupporting structure is provided. The intermediate portion of such adevice may be relatively more flexible than the end portions by, forexample, decreasing the wall thickness of the polymer tube within theintermediate portion.

When a mesh or other supporting structure is provided in combinationwith a polymer tube, the supporting structure may be located around theoutside of the tube, in the inner bore of the tube, or embedded within awall of the tube. More than one supporting structure may be provided, inwhich case each supporting structure may have a different location withrespect to the tube.

One or both of the end portions of the device may include anchoringelements such as hooks, protuberances, or barbs configured to grasp orgrip inner sidewalls of a blood vessel. The radial force of the endportions after expansion may be sufficient to grasp or grip innersidewalls of a blood vessel without anchoring elements.

There need not be a well-defined transition between the intermediate andend portions. For example, mesh type, material, wall thickness,flexibility, etc. may gradually change from an end portion toward anintermediate portion or from an intermediate portion toward an endportion.

The flexibility of the device may increase gradually when moving from anend portion towards the intermediate portion, for example as describedwith respect to the devices 134, 140. The change in flexibility may bedue to change in mesh density (e.g., winding density, window size), tubethickness, or other factors. The flexibility of the device may beuniform or substantially uniform along the entire length of the supportstructure (e.g., stent), or along certain portions of the supportstructure (e.g., along an entire end portion, along the entireintermediate portion, along one end portion and the intermediate portionbut not the other end portion, etc.).

While the devices described herein may be particularly suitable for useas a transvascular shunt in percutaneous surgery, the devices could beused in many other medical applications. For example, the devices couldbe used in angioplasty for the treatment of occluded blood vessels withtortuous or kinked paths, or where the vessels may be subject todeflection or deformation at or near the position of the stent. Thestent could also be used for the repair of damaged blood vessels, forexample in aortic grafting procedures or after perforation during apercutaneous procedure. In certain such cases, the intermediate portionof the device can allow the device to conform to the shape of the bloodvessel and to deform in response to movement of the vessel with reducedrisk of fatigue failure while remaining fixed or anchored in position bythe end portions. For another example, the devices could be used to forma shunt between a healthy artery and a healthy vein for dialysis accessand/or access for administration of medications (e.g., intermittentinjection of cancer therapy, which can damage vessels).

Referring again to FIGS. 4 and 7 , blocking material 251 may be used tohelp inhibit or prevent reversal of arterial blood flow. As will now bedescribed in further detail, additional or other methods and systems canbe used to inhibit or prevent reversal of arterial blood flow, or,stated another way, to inhibit or prevent flow of arterial blood nowflowing into the vein from flowing in the normal, pre-proceduredirection of blood flow in the vein such that oxygenated blood bypassesdownstream tissue such as the foot.

In the absence of treatment, Peripheral Vascular Disease (PVD) mayprogress to critical limb ischemia (CLI), which is characterized byprofound chronic pain and extensive tissue loss that restrictsrevascularization options and frequently leads to amputation. CLI isestimated to have an incidence of approximately 50 to 100 per 100,000per year, and is associated with mortality rates as high as 20% at 6months after onset.

Interventional radiologists have been aggressively trying to treat CLIby attempting to open up chronic total occlusions (CTOs) or bypassingCTOs in the sub-intimal space using such products as the MedtronicPioneer catheter, which tunnels a wire into the sub-intimal spaceproximal to the CTO and then attempts to re-enter the vessel distal tothe occlusion. Once a wire is in place, a user can optionally create awider channel and then place a stent to provide a bypass conduit pastthe occlusion. Conventional approaches such as percutaneous transluminalangioplasty (PTA), stenting, and drug eluting balloons (DEB) to treatPAD can also or alternatively be used in CLI treatment if a wire is ableto traverse the occlusion.

From the amputee-coalition.org website, the following are somestatistics regarding the CLI problem:

-   -   There are nearly 2 million people living with limb loss in the        United States.    -   Among those living with limb loss, the main causes are:        -   vascular disease (54%) (including diabetes and peripheral            artery disease (PAD)),        -   trauma (45%), and        -   cancer (less than 2%).    -   Approximately 185,000 amputations occur in the United States        each year.    -   Hospital costs associated with having a limb amputated totaled        more than $6.5 billion in 2007.    -   Survival rates after an amputation vary based on a variety of        factors. Those who have amputations due to vascular disease        (including PAD and diabetes) face a 30-day mortality rate        reported to be between 9% and 15% and a long-term survival rate        of 60% at 1 year, 42% at 3 years, and 35%-45% at 5 years.    -   Nearly half of the people who lose a limb to dysvascular disease        will die within 5 years. This is higher than the 5-year        mortality rate experienced by people with colorectal, breast,        and prostate cancer.    -   Of people with diabetes who have a lower-limb amputation, up to        55% will require amputation of the second leg within 2 to 3        years.

CLI has been surgically treated by open-leg venous arterialization sincethe early 1900's. Numerous small series of clinical trials have beenpublished over the years using such an open-leg surgical approach, assummarized by a 2006 meta-analysis article by Lu et al. in the EuropeanJournal of Vascular and Endovascular Surgery, vol. 31, pp. 493-499,titled “Meta-analysis of the clinical effectiveness of venousarterialization for salvage of critically ischemic limbs.” The articlehad the following results and conclusions:

-   -   Results:        -   A total of 56 studies were selected for comprehensive            review. No randomized control trial (RCT) was identified.            Seven patient series, comprising 228 patients, matched the            selection criteria. Overall 1-year foot preservation was 71%            (95% CI: 64%-77%) and 1-year secondary patency was 46% (95%            CI: 39%-53%). The large majority of patients in whom major            amputation was avoided experienced successful wound healing,            disappearance of rest pain, and absence of serious            complications.    -   Conclusions:        -   On the basis of limited evidence, venous arterialization may            be considered as a viable alternative before major            amputation is undertaken in patients with “inoperable”            chronic critical leg ischemia.

Among other maladies as described herein, the methods and systemsdescribed herein may be used to create an aterio-venous (AV) fistula inthe below-the-knee (BTK) vascular system using an endovascular,minimally invasive approach. Such methods may be appropriate forpatients that (i) have a clinical diagnosis of symptomatic critical limbischemia as defined by Rutherford 5 or 6 (severe ischemic ulcers orfrank gangrene); (ii) have been assessed by a vascular surgeon andinterventionist and it was determined that no surgical or endovasculartreatment is possible; and/or (iii) are clearly indicated for majoramputation.

In some embodiments, a system or kit optionally comprises one or more ofthe following components: a first ultrasound catheter (e.g., an arterialcatheter, a launching catheter including a needle, etc.); a secondultrasound catheter (e.g., a venous catheter, a target catheter, etc.);and a prosthesis (e.g., a covered nitinol stent graft in a deliverysystem (e.g., a 7 Fr (approx. 2.3 mm) delivery system)). The system orkit optionally further comprises an ultrasound system, a control system(e.g., computer). Some users may already have an appropriate ultrasoundsystem that can be connected to the ultrasound catheter(s). Thecatheters and prostheses described above may be used in the system orkit, and details of other, additional, and/or modified possiblecomponents are described below.

FIG. 14A is a schematic side cross-sectional view of an exampleembodiment of an ultrasound launching catheter 170 comprising a needle172 (e.g., a first ultrasound catheter, an arterial catheter (e.g., ifextending a needle from artery into vein), a venous catheter (e.g., ifextending a needle from vein into artery)). The catheter 170 is placedinto an artery with the needle 172 in a retracted state inside a lumenof the catheter 170. The catheter 170 can be tracked over a guidewire(e.g., a 0.014 inch (approx. 0.36 mm) guidewire) and/or placed through asheath in the artery (e.g., a femoral artery), and advanced up to thepoint of the total occlusion of the artery (in the tibial artery). Thecatheter 170 includes a handle 174 that includes a pusher ring 176.Longitudinal or distal advancement of the pusher ring 176 can advancethe needle 172 from out of a lumen of the catheter 170, out of theartery and into a vein, as described herein. Other advancementmechanisms for the needle 172 are also possible (e.g., rotational,motorized, etc.). Before, after, and/or during after advancing theneedle 172, a guidewire (e.g., a 0.014 inch (approx. 0.36 mm) guidewire)can be placed through the needle 172 (e.g., as described with respect tothe guidewire 14 of FIG. 3 ), and this guidewire can be referred to as acrossing wire.

FIG. 14B is an expanded schematic side cross-sectional view of a distalportion of the ultrasound launching catheter 170 of FIG. 14A within thecircle 14B. Upon advancing or launching, the needle 172 extends radiallyoutwardly from a lumen 173 of the catheter 170. In some embodiments, thelumen 173 ends proximal to the ultrasound transmitting device 178. Theneedle 172 may extend along a path that is aligned with (e.g., parallelto) the path of the directional ultrasound signal emitted by theultrasound transmitting device 178. FIG. 14B also shows the lumen 175,which can be used to house a guidewire for tracking the catheter 170 tothe desired position.

FIG. 15A is a schematic side elevational view of an example embodimentof an ultrasound target catheter 180 (e.g., a second ultrasoundcatheter, an arterial catheter (e.g., if extending a needle from veininto artery), a venous catheter (e.g., if extending a needle from arteryinto vein)). FIG. 15B is an expanded schematic side cross-sectional viewof the ultrasound target catheter 180 of FIG. 15A within the circle 15B.FIG. 15C is an expanded schematic side cross-sectional view of theultrasound target catheter 180 of FIG. 15A within the circle 15C. Thecatheter 180 can be tracked over a guidewire (e.g., a 0.014 inch(approx. 0.36 mm) guidewire) and/or placed through a sheath in the vein(e.g., a femoral vein), and advanced up to a point (e.g., in the tibialvein) proximate and/or parallel to the distal end of the catheter 170and/or the occlusion in the artery. The catheter 180 includes anultrasound receiving transducer 182 (e.g., an omnidirectional ultrasoundreceiving transducer) that can act as a target in the vein for aligningthe needle 172 of the catheter 170. The catheter 180 may be left inplace or remain stationary or substantially stationary while thecatheter 170 is rotated and moved longitudinally to obtain a good oroptimal ultrasound signal indicating that the needle 172 is aligned withand in the direction of the catheter 180.

The catheters 170, 180 may be connected to an ultrasound transceiverthat is connected to and controlled by a computer running transceiversoftware. As described in further detail herein, the catheter 170includes a flat or directional ultrasound transmitter 178 configured totransmit an ultrasound signal having a low angular spread or tight beam(e.g., small beam width) in the direction of the path of the needle 172upon advancement from the lumen 173 of the catheter 170. The catheter180 includes an omnidirectional (360 degrees) ultrasound receiver 182configured to act as a target for the ultrasound signal emitted by thedirectional transmitter 178 of the catheter 170. The catheter 170 isrotated until the peak ultrasound signal is displayed, indicating thatthe needle 172 is aligned to the catheter 180 such that, upon extensionof the needle 172 (e.g., by longitudinally advancing the ring 176 of thehandle 174), the needle 172 can pass out of the artery in which thecatheter 170 resides, through interstitial tissue, and into the vein inwhich the catheter 180 resides.

FIG. 16 is an example embodiment of a graph for detecting catheteralignment, as may be displayed on display device of an ultrasound system(e.g., the screen of a laptop, tablet computer, smartphone, combinationsthereof, and the like). The graph in FIG. 16 shows that the signaloriginating from the transmitting catheter in the artery has beenreceived by the receiving catheter in the vein. The second frequencyenvelope from the right is the received signal. The distance from theleft side of the illustrated screen to the leading edge of the secondfrequency envelope may indicate the distance between the catheters. Theoperator can move the catheter in the artery both rotationally andlongitudinally, for example until the second envelope is maximal, whichindicates the catheters are correctly orientated.

FIG. 17 is a schematic side elevational view of an example embodiment ofa prosthesis (e.g., stent, stent-graft) delivery system 190. In someembodiments, the delivery system 190 is a 7 Fr (approx. 2.3 mm) deliverysystem. FIG. 18 is a schematic side elevational view of an exampleembodiment of a prosthesis (e.g., stent, stent-graft) 200. In FIG. 17 ,a prosthesis (e.g., the prosthesis 200, other prostheses describedherein, etc.) is in a compressed or crimped state proximate to thedistal end 192 of the delivery system 190. In some embodiments, theprosthesis 200 comprises a shape-memory stent covered with a graftmaterial, for example as described above. Once the crossing wire extendsfrom the artery to the vein, for example as a result of being advancedthrough the needle 172 as described herein, the delivery system 190 canbe advanced over the crossing wire. The prosthesis 200 may be deployedfrom the delivery system 190, for example by squeezing the triggerhandle 194 of the delivery system 190, causing the outer cover sheath toproximally retract and/or distally advance the prosthesis 200. Theprosthesis 200 can create a flow path between the artery and the veinand through the interstitial tissue. Other types of delivery systems andprostheses are also possible.

Referring again to FIG. 17 , some non-limiting example dimensions of thedelivery system 190 are provided. The distance 196 of travel of thetrigger handle 194 may be, for example, between about 0.4 inches(approx. 1 cm) and about 12 inches (approx. 30 cm), between about 1 inch(approx. 2.5 cm) and about 8 inches (approx. 20 mm), or between about 2inches (approx. 5 cm) and about 6 inches (approx. 15 mm) (e.g., about 2inches (approx. 5 cm)). In some embodiments, the distance 196 of travelof the trigger handle 194 is at least as long as the length of theprosthesis 200 to be deployed (e.g., in the radially expanded state). Insome embodiments, gearing or other mechanisms may be employed to reducethe distance 196 of travel of the trigger handle 194 be less than thelength of the prosthesis 200 to be deployed (e.g., in the radiallyexpanded state). The distance 196 may be adjusted for example, based onat least one of: the length of the prosthesis 200 to be deployed, thedegree of foreshortening of the prosthesis 200 to be deployed, themechanism of deployment (e.g., whether the outer sheath is proximallyretracted, the prosthesis 200 is pushed distally forward, or both,whether the delivery system 190 includes gearing mechanism, etc.),combinations thereof, and the like. The length 197 of the outer sheathor catheter portion may be, for example, between about 40 inches(approx. 1,020 mm) and about 50 inches (approx. 1,270 mm), between about46 inches (approx. 1,170 mm) and about 47 inches (approx. 1,190 mm), orbetween about 46.48 inches (approx. 1,180 mm) and about 46.7 inches(approx. 1,186 mm). The total length 198 of the delivery system 190 fromproximal tip to distal tip may be, for example, between about 40 inches(approx. 1,000 mm) and about 60 inches (approx. 1,500 mm). The lengths197, 198 may be adjusted, for example based on at least one of: lengthof the prosthesis 200 to be deployed, the degree of foreshortening ofthe prosthesis 200 to be deployed, the height of the patient, thelocation of the occlusion being treated, combinations thereof, and thelike. In some embodiments, spacing the trigger handle 194 from thevascular access point, for example by between about 10 cm and about 30cm (e.g., at least about 20 cm) may advantageously provide easierhandling or management by the user. In certain such embodiments, thelength 197 may be between about 120 cm and about 130 cm (e.g., for anantegrade approach) or between about 150 cm and about 180 cm (e.g., fora contralateral approach).

Referring again to FIG. 18 , some non-limiting example dimensions of theprosthesis 200 are provided, depending on context at least in thecompressed state. The thickness 201 of a structural strut may be, forexample, between about 0.05 mm and about 0.5 mm or between about 0.1 mmand about 0.2 mm (e.g., about 0.143 mm). The spacing 202 between strutsof a structural strut may be, for example, between about 0.005 mm andabout 0.05 mm or between about 0.01 mm and about 0.03 mm (e.g., about0.025 mm). The thickness 203 of a linking strut may be, for example,between about 0.05 mm and about 0.5 mm or between about 0.1 mm and about0.2 mm (e.g., about 0.133 mm). The longitudinal length 204 of thestructural components may be, for example, between about 1 mm and about5 mm or between about 2.5 mm and about 3 mm (e.g., about 2.8 mm). Thelongitudinal length 205 between structural components may be, forexample, between about 0.25 mm and about 1 mm or between about 0.5 mmand about 0.6 mm (e.g., about 0.565 mm). The length 206 of a strutwithin a structural component, including all portions winding back andforth, may be, for example, between about 25 mm and about 100 mm orbetween about 65 mm and about 70 mm (e.g., about 67.62 mm). The totallongitudinal length of the prosthesis 200 may be, for example, betweenabout 25 mm and about 150 mm or between about 50 mm and about 70 mm(e.g., about 62 mm). As described herein, a wide variety of laser-cutstents, woven stents, and combinations thereof, including variousdimensions, are possible. The struts described herein may comprise wiresor filaments or potions not cut from a hypotube or sheet.

The proximal and/or distal ends of the prosthesis 200 may optionallycomprise rings 210. The rings 210 may, for example, help to anchor theprosthesis 200 in the artery and/or the vein. The circumferential width211 of a ring 210 may be, for example, between about 0.25 mm and about 1mm or between about 0.5 mm and about 0.75 mm (e.g., about 0.63 mm). Thelongitudinal length 212 of a ring 210 may be, for example, between about0.25 mm and about 2 mm or between about 0.5 mm and about 1 mm (e.g.,about 0.785 mm). In some embodiments, a ratio of the total length of theprosthesis 200 to the longitudinal length 212 of a ring 210 may bebetween about 50:1 and about 100:1 (e.g., about 79:1). The dimensions211, 212 of the rings 210 may be adjusted, for example based on at leastone of: strut thickness, diameter of the prosthesis (e.g., relative tothe vessel), total length of the prosthesis, material, shape settingproperties, combinations thereof, and the like.

FIG. 19 is a schematic side elevational view of another exampleembodiment of a prosthesis 220. The prosthesis 200 may have the shape ofthe prosthesis 220, for example in a radially expanded state (e.g., uponbeing deployed from the delivery system 190). FIG. 19 illustrates anexample shape of the prosthesis 220 comprising a first portion 221 and asecond portion 225. The first portion 221 has a substantiallycylindrical or cylindrical shape having a length 222 between about 15 mmand about 25 mm (e.g., about 21 mm) and a diameter 223 between about 2.5mm and about 5 mm (e.g., about 3.5 mm). The second portion 225 has asubstantially frustoconical or frustoconical shape having a length 226between about 30 mm and about 50 mm (e.g., about 41 mm) and a widestdiameter 227 between about 4 mm and about 10 mm, between about 4 mm andabout 7 mm (e.g., about 5.5 mm), etc. The angle of taper of the secondportion 225 away from the first portion 221 may be between about 0.02degrees and about 0.03 degrees (e.g., about 0.024 degrees).

Further details regarding prostheses that can be used in accordance withthe methods and systems described herein are described in U.S. patentapplication Ser. No. 13/791,185, filed Mar. 8, 2013, which is herebyincorporated by reference in its entirety.

FIGS. 20A-20H schematically illustrate an example embodiment of a methodfor effecting retroperfusion. The procedure will be described withrespect to a peripheral vascular system such as the lower leg, but canalso be adapted as appropriate for other body lumens (e.g., cardiac,other peripheral, etc.). Certain steps such as anesthesia, incisionspecifics, suturing, and the like may be omitted for clarity. In someembodiments, the procedure can be performed from vein to artery (e.g.,with the venous catheter coming from below).

Access to a femoral artery and a femoral vein is obtained. An introducersheath (e.g., 7 Fr (approx. 2.3 mm)) is inserted into the femoral arteryand an introducer sheath (e.g., 6 Fr (approx. 2 mm)) is inserted intothe femoral vein, for example using the Seldinger technique. A guidewire(e.g., 0.014 inch (approx. 0.36 mm), 0.035 inch (approx. 0.89 mm), 0.038inch (approx. 0.97 mm)) is inserted through the introducer sheath in thefemoral artery and guided into the distal portion of the posterior oranterior tibial diseased artery 300. A second guidewire (e.g., 0.014inch (approx. 0.36 mm), 0.035 inch (approx. 0.89 mm), 0.038 inch(approx. 0.97 mm)) or a snare is inserted through the introducer sheathin the femoral vein. In embodiments in which a snare is used, thedescribed third guidewire, fourth guidewire, etc. described herein areaccurate even though the numbering may not be sequential.

A venous access needle is percutaneously inserted into a target vein,for example a tibial vein (e.g., the proximal tibial vein (PTV)). Insome embodiments, the venous access needle may be guided underultrasound. In some embodiments, contrast may be injected into thesaphenous vein towards the foot (retrograde), and then the contrast willflow into the PTV. This flow path can be captured using fluoroscopy suchthat the venous access needle can be guided by fluoroscopy rather thanor in addition to ultrasound.

The target vein may be accessed proximate to and distal to (e.g., a fewinches or centimeters) below where the launching catheter 310 willlikely reside. In some embodiments, the target vein may be in the ankle.Once the venous access needle is in the vein, a third guidewire (or“second” guidewire in the case that a snare is used instead of a secondguidewire) is inserted into the venous access needle and advancedantegrade in the target vein up to the femoral vein. This access methodcan advantageously reduce issues due to advancing wires retrogradeacross venous valves, which are described in further detail below. Thethird guidewire is snared, for example using fluoroscopic guidance, andpulled through the femoral vein sheath. The target catheter 320 isinserted into the femoral vein sheath over the third guidewire, whichhas been snared. The target catheter 320 is advanced over the thirdguidewire into the venous system until the target catheter is proximateto and/or parallel with the guidewire in the distal portion of theposterior or anterior tibial diseased artery and/or proximate to theocclusion 304, as shown in FIG. 20A.

In some embodiments, the third guidewire may include an ultrasoundreceiving transducer (e.g., omnidirectional) mounted to provide thetarget for the signal emitted by the launching catheter 310 or thetarget catheter 320 could be tracked over the third guidewire, either ofwhich may allow omission of certain techniques (e.g., femoral veinaccess, introducing vein introducer sheath, inserting second guidewire,antegrade advancing of the third guidewire up to the femoral vein,snaring the third guidewire, advancing the target catheter 320 over thethird guidewire).

In some embodiments, the PTV may be accessed directly, for example usingultrasound, which can allow placement of the target catheter 320directly into the PTV, for example using a small sheath. which may allowomission of certain techniques (e.g., femoral vein access, introducingvein introducer sheath, inserting second guidewire, antegrade advancingof the third guidewire up to the femoral vein).

In some embodiments, the catheter 320 is not an over-the-wire catheter,but comprises a guidewire and an ultrasound receiving transducer (e.g.,omnidirectional). The catheter 320 may be inserted as the thirdguidewire, as discussed above, as the second guidewire, or as aguidewire through a small sheath when directly accessing the PTV.

Ultrasound transducers generally include two electrodes includingsurfaces spaced by a ceramic that can vibrate. An incoming or receivedultrasound signal wave can couple into a length extensional mode, asshown in FIG. 21 . FIG. 21 is a schematic perspective view of an exampleembodiment of an ultrasound receiving transducer 350. If the proximal ortop end 352 of the transducer 350 and the distal or bottom end 354 ofthe transducer are conductive and electrically connected to wires, thetransducer can receive ultrasound signals. In some embodiments, thetransducer 350 has a length 356 between about 0.1 mm and about 0.4 mm(e.g., about 0.25 mm). In some embodiments, the transducer 350 has anoverlap length 358 between about 0.1 mm and about 0.3 mm (e.g., about0.2 mm). In some embodiments, the transducer 350 has a diameter that issimilar to, substantially similar to, or the same as the guidewire onwhich it is mounted. In some embodiments, an array or series oflaminates may enhance the signal-receiving ability of the transducer350.

In some embodiments, a guidewire comprising an ultrasound receivingtransducer may comprise a piezoelectric film (e.g., comprising plastic),which could enhance the signal-receiving ability of the transducer. FIG.22 is a schematic cross-sectional view of another example embodiment ofan ultrasound receiving transducer 360. The ultrasound receivingtransducer 360 shown in FIG. 22 includes an optional lumen 368. Theultrasound receiving transducer 360 includes a series of layers 362,364, 366. The layer 362 may comprise a polymer (e.g., polyvinylidenefluoride (PVDF)) layer. The layer 364 may comprise an inorganic compound(e.g., tungsten carbide) layer. The layer 366 may comprise a polymer(e.g., polyimide) layer. The layer 366 may have a thickness betweenabout 25 micrometers (μm or microns) and about 250 μm (e.g., at leastabout 50 μm).

The launching catheter 310 is tracked over the guidewire in the femoraland tibial arteries proximate to and proximal to the occlusion 304, asshown in FIG. 20B. The catheter 310 may be more proximal to theocclusion 304 depending on suitability at that portion of the anatomyfor the retroperfusion process. In some embodiments, the catheter 310may be positioned in the distal portion of the posterior or anteriortibial artery, for example proximate to the catheter 320. In someembodiments, the catheter 310 may be positioned within a few inches orcentimeters of the ankle.

The launching catheter 310 emits a directional ultrasound signal. Asshown by the arrow 311, 312 in FIG. 20C, the launching catheter 310 isrotated and moved longitudinally until the signal is received by thetarget catheter 320. Once the signal is received, which indicatesalignment such that extension of the needle form the launching catheter310 will result in successful access of the vein, a crossing needle 314is advance out of the catheter 310, out of the tibial artery 300 andinto the tibial vein 302, as shown in FIG. 20D. Accuracy of theplacement of the crossing needle 314 to form a fistula between theartery 300 and the vein 302 may be confirmed, for example, usingcontrast and fluoroscopy.

In some embodiments, the ultrasound signal can be used to determine thedistance between the artery 300 and the vein 302. Referring again toFIG. 16 , the distance from the left side of the illustrated screen tothe leading edge of the second frequency envelope can be used as anindicator of distance between the catheters.

Referring again to FIG. 16 , a display device may graphically showsignal alignment peaks to allow the user to determine the alignmentposition. In some embodiments, the signal alignment may change colorabove or below a threshold value, for example from red to green. In someembodiments, an audio signal may be emitted, for example when analignment signal crosses over a threshold value, which can allow a userto maintain focus on the patient rather than substantially continuouslymonitoring a screen.

In some embodiments, a horizontal line on the screen may move up toindicate the maximum signal value or peak achieved to that point duringthe procedure. This line may be called “peak hold.” If a greater signalvalue is achieved, the horizontal line moves to match that higher value.If no manipulation is able to raise the peak above the horizontal line,that can indicate maximum alignment. If the signal peak falls a certainamount below the horizontal line, the catheters may have moved and nolonger be properly aligned. Since the level of alignment indicated bythe horizontal line has previously been achieved during the procedure,the user knows that such a level of alignment can be achieved by furtherrotational and/or longitudinal manipulation.

A fourth guidewire 316 (e.g., 0.014 inch (approx. 0.36 mm)) (or “third”guidewire in the case that a snare is used instead of a secondguidewire) is placed through the lumen of the crossing needle 314 of thecatheter 310 and into the tibial vein 302 in a retrograde direction (ofthe vein 302) towards the foot, as shown in FIG. 20E. External cuffpressure may be applied above the needle crossing point to reduce flowin the artery 300 to inhibit or prevent formation of a hematoma, and/orto engorge the vein to facilitate valve crossing. The catheters 310, 320may be removed, leaving the guidewire 316 in place, extending from theintroducer sheath in the femoral artery, through the arterial tree, andinto the tibial vein 302.

Certain techniques for crossing a guidewire 316 from an artery 300 to avein 302 may be used instead of or in addition to the directionalultrasound techniques described herein.

In some embodiments, a tourniquet can be applied to the leg, which canincrease vein diameters. In some embodiments, a blocking agent (e.g., asdiscussed with respect to FIGS. 4 and 7 , a blocking balloon, etc.) maybe used to increase vein diameter. For example, venous flow could backup, causing dilation of the vein. A larger vein diameter can produce alarger target for the crossing needle 314, making the vein 300 easier toaccess with the crossing needle 314.

In some embodiments, a PTA balloon can be used in the target vein, and aneedle catheter (e.g., Outback, available from Cordis) can target thePTA balloon under fluoroscopy. The crossing needle 314 can puncture thePTA balloon, and the reduction in pressure of the PTA balloon canconfirm proper alignment of the crossing needle 314. The PTA balloon canincrease vein diameter, producing a larger target for the crossingneedle 314, making the vein 300 easier to access with the crossingneedle 314. The guidewire 316 may be advanced through the crossingneedle 314 and into the PTA balloon.

In some embodiments, the PTA balloon comprises a mesh (e.g., a wovenmesh), for example embedded in the polymer of the balloon. When aballoon without such a mesh is punctured, the balloon material couldrupture and cause emboli (e.g., pieces of the balloon floatingdownstream). The mesh can help to limit tearing of the balloon material,which can inhibit or prevent balloon material from causing emboli. Insome implementations, a balloon without a mesh can be configured tosnare a guidewire upon being collapsed (e.g., by entangling theguidewire in folds of the balloon), whether or not punctured.

In some embodiments, two PTA balloons spaced longitudinally along theaxis of the catheter can be used in the target vein, and a needlecatheter can target the one of the PTA balloons. Upon puncturing of oneof the PTA balloons by the crossing needle 314, contrast in a wellbetween the PTA balloons can be released because the punctured balloonno longer acts as a dam for the contrast. The release of contrast can bemonitored using fluoroscopy. The PTA balloons can be on the samecatheter or on different catheters.

In some embodiments, two PTA balloons spaced longitudinally along theaxis of the catheter can be used in the target vein, and a needlecatheter can target the space or well between the PTA balloons. Uponpuncturing of the well by the crossing needle 314, contrast in the wellcan be disturbed. The disturbance of contrast can be monitored usingfluoroscopy. The PTA balloons can be on the same catheter or ondifferent catheters.

In some embodiments in which a PTA balloon may be used in combinationwith an ultrasound target in the target vein, a PTA balloon catheterincludes a PTA balloon and an ultrasound receiving transducer (e.g.,omnidirectional). In certain such embodiments, the launching catheter310 can target the PTA balloon under fluoroscopy and/or can target theultrasound receiving transducer as described herein. The crossing needle314 can puncture the PTA balloon, and the reduction in pressure of thePTA balloon can confirm proper alignment of the crossing needle 314. ThePTA balloon can increase vein diameter, producing a larger target forthe crossing needle 314, making the vein 300 easier to access with thecrossing needle 314. The guidewire 316 may be advanced through thecrossing needle 314 and into the PTA balloon.

In some embodiments, a LeMaitre device (e.g., the UnBalloon™Non-Occlusive Modeling Catheter, available from LeMaitre Vascular ofBurlington, Mass.) can be used in the target vein. In some embodiments,a LeMaitre device can increase vein diameters. A larger vein diametercan produce a larger target for the crossing needle 314, making the vein300 easier to access with the crossing needle 314. In some embodiments,the needle 314 can penetrate into the LeMaitre device. In certain suchembodiments, the LeMaitre device can act as a mesh target (e.g.,comprising radiopaque material visible under fluoroscopy) for thecrossing needle 314. The mesh of the LeMaitre device can be radiallyexpanded by distally advancing a proximal portion of the mesh and/orproximally retracting a distal portion of the mesh (e.g., pushing theends together like an umbrella) and/or by allowing the mesh toself-expand (e.g., in embodiments in which at least some parts of themesh comprise shape-memory material). In some embodiments, a LeMaitredevice can grip a crossing wire to hold the crossing wire in the targetvein as the LeMaitre device closes.

In some embodiments, the launching catheter 310 may comprise a firstmagnet having a first polarity and the target catheter 320 may comprisea second magnet having a second polarity. When the magnets are closeenough for magnetic forces to move one or both of the catheters 310,320, the crossing needle 314 may be advanced to create the fistulabetween the artery 300 and the vein 302. In some embodiments, the firstmagnet maybe circumferentially aligned with the crossing needle 314and/or the launching catheter 310 may be magnetically shielded toprovide rotational alignment. In some embodiments, the second magnet maybe longitudinally relatively thin to provide longitudinal alignment. Insome embodiments, the crossing needle 314 and/or the guidewire 316 maybe magnetically pulled from the artery 300 to the vein 302, or viceversa. Some systems may include both ultrasound guidance and magneticguidance. For example, ultrasound guidance could be used for initialalignment and magnetic guidance could be used for refined alignment.

Referring again to FIGS. 20A-20H, a prosthesis delivery system 330carrying a prosthesis 340 is tracked over the guidewire 316 through theinterstitial space between the artery 300 and the vein 300 and then intothe vein 302, as shown in FIG. 20F. In some embodiments, a separate PTAballoon catheter (e.g., about 2 mm) can be tracked over the guidewire316 to pre-dilate the fistula between the artery 300 and the vein 302prior to introduction of the prosthesis delivery system 330. Use of aPTA balloon catheter may depend, for example, on the radial strength ofthe prosthesis 340.

The prosthesis 340 is deployed from the prosthesis delivery system 330,for example by operating a trigger handle 194 (FIG. 17 ). In someembodiments, for example if the prosthesis 340 is not able to expandand/or advance, the prosthesis delivery system 330 may be removed and aPTA catheter (e.g., about 2 mm) advanced over the guidewire 316 toattempt to dilate or further dilate the fistula the artery 300 and thevein 302. Deployment of the prosthesis 340 may then be reattempted(e.g., by self-expansion, balloon expansion, etc.). In some embodiments,deployment of the prosthesis 340 may remodel a vessel, for exampleexpanding the diameter of the vessel by at least about 10%, by at leastabout 20%, by at least about 30%, or more, by between about 0% and about10%, by between about 0% and about 20%, by between about 0% and about30%, or more. In embodiments in which the prosthesis 340 isself-expanding, the degree of remodeling may change over time, forexample the prosthesis 340 expanding as the vessel expands orcontracting when the vessel contracts.

Once the prosthesis 340 is deployed, as shown in FIG. 20G, the fistulamay be dilated with a PTA catheter. The diameter of the PTA catheter(e.g., about 3 mm to about 6 mm) may be selected based at least in parton: the diameter of the artery 300, the diameter of the vein 302, thecomposition of the interstitial tissue, the characteristics of theprosthesis 340, combinations thereof, and the like. In some embodiments,the prosthesis delivery system 330 may comprise a PTA balloon catheter(e.g., proximal or distal to the prosthesis 340) usable for one,several, or all of the optional PTA balloon catheter techniquesdescribed herein. In embodiments in which the prosthesis comprises aconical portion, the PTA balloon may comprise a conical portion. Oncethe prosthesis 340 is in place, the prosthesis delivery system 330 maybe removed, as shown in FIG. 20H. An AV fistula is thereby formedbetween the artery 300 and the vein 302. Confirmation of placement ofvarious catheters 310, 320, 330 and the prosthesis 340 may be confirmedthroughout parts or the entire procedure under fluoroscopy usingcontrast injections.

In some embodiments, a marker (e.g., a clip a lancet, scissors, apencil, etc.) may be applied (e.g., adhered, placed on top of, etc.) tothe skin to approximately mark the location of the fistula formedbetween the artery 300 and the vein 302 by the crossing needle 314 priorto deployment of the prosthesis 340. In embodiments in which the useruses a sphygmomanometer inflated above the fistula to avoid bleeding,the lack of blood flow can render visualization or even estimation ofthe fistula site difficult, and the marker can provide suchidentification. In embodiments in which the transmitting and receivingcatheters are removed after fistula formation, the cross-over point maybe difficult for the user to feel or determine, and the marker canprovide such identification. If the fistula is to be dilated, a midpointof the dilation balloon may be preferably aligned with the midpoint ofthe fistula (e.g., to increase or maximize the hole-through interstitialspace). In some embodiments, the marker may be visualized underfluoroscopy (e.g., comprising radiopaque material) to allow the user tosee and remember the location of the fistula under fluoroscopy prior todeployment of the prosthesis 340.

Once the prosthesis 340 is in place, an obstacle to blood flowingthrough the vein 302 and into the foot are the valves in the veins.Steering a guidewire across venous valves can be a challenge, forexample because pressure from the artery may be insufficient to extendthe veins and make the valves incompetent. The Applicant has discoveredthat venous valves distal to the AV fistula can be disabled or madeincompetent using one or more of a variety of techniques such as PTAcatheters, stents (e.g., covered stents, stent-grafts, etc.), and avalvulotome, as described in further detail below. Disabling venousvalves can allow blood to flow via retroperfusion from the femoralartery, retrograde in the vein 302, and retrograde in the vein to thevenuoles and capillaries to the distal part of the venous circulation ofthe foot to provide oxygenated blood to the foot in CLI patients.

In some embodiments, a high-pressure PTA balloon catheter may be used tomake venous valves incompetent (e.g., when inflated to greater thanabout 10 atm (approx. 1,013 kilopascals (kPa))).

In some embodiments, one or more stents can be placed across one or morevenous valves to render those valves incompetent. For example, suchstents should have sufficient radial force that the valves stay open.The stent may forcefully rupture the valves. In some embodiments, thestent comprises a covering or a graft. Certain such embodiments cancover venous collateral vessels. In some embodiments, the stent is bareor free of a covering or graft. Certain such embodiments can reducecosts. The venous stent may extend along a length (e.g., an entirelength) of the vein. For example, in some embodiments, the entire lengthof the PTV is lined with a covered stent, covering the venouscollaterals, disrupting venous valves.

In some embodiments, the venous stent is separate from the fistulaprosthetic. A separate venous stent may allow more flexibility inproperties such as dimensions (e.g., length, diameter), materials (e.g.,with or without a covering or graft), and other properties. FIG. 31Aschematically illustrates an example embodiment of an arteriovenousfistula stent 340 separate from an example embodiment of a venous stent342. The venous stent 342 may be spaced from the fistula stent 340(e.g., as illustrated in FIG. 31A), abutting the fistula stent 340, oroverlapping, telescoping, or coaxial with the fistula stent 340 (e.g., adistal segment of the fistula stent 340 being at least partially insidea proximal segment of the venous stent 342 or a proximal segment of thevenous stent 342 being at least partially inside a distal segment of thefistula stent 340). In embodiments in which the fistula stent 340 andthe venous stent 342 overlap, placement of the venous stent 342 firstcan allow the proximal end of the venous stent 342, which faces thedirection of retrograde blood flow, to be covered by the fistula stent340 to reduce or eliminate blood flow disruption that may occur due thedistal end of the venous stent 342. In embodiments in which the fistulastent 340 and the venous stent 342 overlap, placement of the venousstent 342 second can be through the fistula stent 340 such that bothstents 340, 342 can share at least one deployment parameter (e.g.,tracking stent deployment devices over the same guidewire). The venousstent 342 may be deployed before or after the fistula stent 340. Thevenous stent 342 may have a length between about 2 cm and about 30 cm(e.g., about 2 cm, about 3 cm, about 4 cm, about 5 cm, about 6 cm, about7 cm, about 8 cm, about 9 cm, about 10 cm, about 11 cm, about 12 cm,about 13 cm, about 14 cm, about 15 cm, about 16 cm, about 17 cm, about18 cm, about 19 cm, about 20 cm, about 21 cm, about 22 cm, about 23 cm,about 24 cm, about 25 cm, about 26 cm, about 27 cm, about 28 cm, about29 cm, about 30 cm, ranges between such values, etc.).

In some embodiments, the venous stent is integral with the fistulaprosthetic. An integral venous stent may allow more flexibility inproperties such as dimensions (e.g., length, diameter), materials (e.g.,with or without a covering or graft), and other properties. FIG. 31Bschematically illustrates an example embodiment arteriovenous fistulastent 344 comprising an integrated venous stent. FIG. 31C schematicallyillustrates an example embodiment of fistula stent 344 comprising anintegrated venous stent. The stent 344 comprises a first portion 346configured to anchor in an artery, a second portion 350 configured toanchor in and line a length of a vein, and a third portion 348longitudinally between the first portion 346 and the second portion 350.In embodiments in which the first portion 346 and the second portion 350have different diameters (e.g., as illustrated in FIG. 31C), the thirdportion 348 may be tapered. In some embodiments, a portion of the secondportion 350 that is configured to line a vein has a different property(e.g., diameter, material, radial strength, combinations thereof, andthe like) than other portions of the second portion 350. A length of thesecond section 350 may be greater than a length of the first section346. For example, the second section 350 may have a length configured toline a vessel such as the PTV. The second section 350 may have a lengthbetween about between about 2 cm and about 30 cm (e.g., about 2 cm,about 3 cm, about 4 cm, about 5 cm, about 6 cm, about 7 cm, about 8 cm,about 9 cm, about 10 cm, about 11 cm, about 12 cm, about 13 cm, about 14cm, about 15 cm, about 16 cm, about 17 cm, about 18 cm, about 19 cm,about 20 cm, about 21 cm, about 22 cm, about 23 cm, about 24 cm, about25 cm, about 26 cm, about 27 cm, about 28 cm, about 29 cm, about 30 cm,ranges between such values, etc.).

In some in situ bypass procedures, a saphenous vein is attached to anartery in the upper leg and another artery in the lower leg, bypassingall blockages in the artery. In certain such procedures, the vein is notstripped out of the patient, flipped lengthwise, and used as aprosthesis, but rather is left in place so that blood flow is retrograde(against the valves of the vein). A standard valvulotome may be placedinto the saphenous vein from below and advanced to the top in acollapsed state, opened, and then pulled backwards in an open state,cutting venous valves along the way. Cutting surfaces of suchvalvulotomes face backwards so as to cut during retraction during theseprocedures. FIG. 23A is a schematic perspective view of an exampleembodiment of a valvulotome 400 that may be used with such procedures,including blades 402 facing proximally.

In some embodiments of the methods described herein, access distal tothe vein valves is not available such that pulling a valvulotomebackwards is not possible, but pushing a reverse valvulotome asdescribed herein forward is possible. FIG. 23B is a schematicperspective view of an example embodiment of a valvulotome 410 that maybe used with such procedures. The reverse valvulotome 410 includes oneor a plurality of blades 412 (e.g., two to five blades (e.g., threeblades)) facing forward or distal such that valves can be cut as thereverse valvulotome 410 is advanced distally. At least becauseretrograde access to veins to be disabled has not previously beenrecognized as an issue, there has been no prior motivation to reversethe direction of the blades of a valvulotome to create a reversevalvulotome 410 such as described herein. The reverse valvulotome 410may be tracked over a guidewire 414, which can be steered into theveins, for making the venous valves incompetent. After forming a fistulabetween an artery and a vein as described herein, the flow of fluid inthe vein is in the direction opposite the native or normal orpre-procedure direction of fluid flow in the vein such that pushing thereverse valvulotome 410 is in a direction opposite native fluid flow butin the direction of post-fistula fluid flow.

Other systems and methods are also possible for making the valves in thevein incompetent (e.g., cutting balloons, atherectomy, laser ablation,ultrasonic ablation, heating, radio frequency (RF) ablation, a catheterwith a tip that is traumatic or not atraumatic (e.g., an introducersheath) being advanced and/or retracted, combinations thereof, and thelike).

Crossing vein valves in a retrograde manner before such valves are madeincompetent can also be challenging. FIG. 24 is a schematic perspectiveview of an example embodiment of a LeMaitre device 420 that may be usedto radially expand the veins, and thus their valves. The LeMaitre device420 includes an expandable oval or oblong leaf shape 422, for example aself-expanding nitinol mesh. In some embodiments, a PTA balloon cathetermay be used to radially expand the veins, and thus their valves. In someembodiments, application of a tourniquet to the leg can radially expandthe veins, and thus their valves. Upon radial expansion, a guidewire canbe advanced through the stretched valve(s) (e.g., through an expansiondevice such as the LeMaitre device) and catheters (e.g., PTA, stentdelivery, atherectomy (e.g., directional, orbital, laser, etc.), etc.)or other over-the-wire devices can be advanced over the guidewire.

FIGS. 26A and 26B schematically illustrate another example embodiment ofa method for effecting retroperfusion. Referring again to FIG. 20E, afistula may be created between an artery 600 including an occlusion 604and a vein 602 with a guidewire 606 extending therethrough using one ormore of the techniques described herein and/or other techniques. Aprosthesis delivery system carrying a prosthesis 620 is tracked over theguidewire 606 through the interstitial space between the artery 600 andthe vein 602 and then into the vein 602, as shown in FIG. 26A. In someembodiments, a separate PTA balloon catheter (e.g., about 2 mm) can betracked over the guidewire 606 to pre-dilate the fistula between theartery 600 and the vein 602 prior to introduction of the prosthesisdelivery system. Use of a PTA balloon catheter may depend, for example,on the radial strength of the prosthesis 620. The prosthesis 620 may bethe stent 500, 520, 540 of FIGS. 25A-25C or variations thereof (e.g., asdescribed with respect to FIG. 25C), which include uncovered and lowporosity woven filaments configured to divert blood flow.

The flow diverting properties of uncovered woven filaments may depend oncertain hemodynamic characteristics of the vascular cavities. Forexample, if the occlusion 604 is not total such that some pressure dropmay occur between the lumen of the prosthesis 620 and the portion of theartery 600 between the occlusion 604 and the prosthesis 620, blood maybe able to flow through the sidewalls of the prosthesis 620 rather thaninto the fistula. Referring again to FIG. 4 and the description of theblocking material 251, blocking material 608 may optionally be providedin the artery 600 to further occlude the artery 600, which can inhibithemodynamic effects that might cause and/or allow blood to flow throughthe sidewalls of the prosthesis 620. For another example, a pressuredrop between the artery 600 and the vein 602 might cause and/or allowblood to flow through the sidewalls of the prosthesis in the normaldirection of venous blood flow rather than through the lumen of theprosthesis to effect retroperfusion. Referring again to FIG. 4 and thedescription of the blocking material 251, blocking material 610 mayoptionally be provided in the vein 602 to occlude the portion of thevein 602 downstream to the fistula under normal venous flow, which caninhibit hemodynamic effects that might cause and/or allow blood to flowthrough the sidewalls of the prosthesis 620.

The prosthesis 620 is deployed from the prosthesis delivery system, forexample by operating a trigger handle 194 (FIG. 17 ). In someembodiments, for example if the prosthesis 620 is not able to expandand/or advance, the prosthesis delivery system may be removed and a PTAcatheter (e.g., about 2 mm) advanced over the guidewire 620 to attemptto dilate or further dilate the fistula the artery 600 and the vein 602.Deployment of the prosthesis 620 may then be reattempted (e.g., byself-expansion, balloon expansion, etc.). In some embodiments,deployment of the prosthesis 620 may remodel a vessel, for exampleexpanding the diameter of the vessel as described herein. In embodimentsin which the prosthesis 620 is self-expanding, the degree of remodelingmay change over time, for example the prosthesis 620 expanding as thevessel expands or contracting when the vessel contracts. The prosthesis620 may be conformable to the anatomy in which the prosthesis 620 isdeployed. For example, in an expanded state on a table or benchtop, theprosthesis 620 may be substantially cylindrical, but the prosthesis 620may conform to the diameters of the vessels and fistula in which theprosthesis 620 is deployed such that the prosthesis may have differentdiameters in different longitudinal segments, tapers, non-cylindricalshapes, combinations thereof, and the like.

In some embodiments in which the prosthesis 620 comprises a supplementalsupport structure (e.g., as described with respect to FIG. 25B),deployment of the prosthesis may comprise deploying the first wovenstructure and, before, during, and/or after deploying the first wovenstructure, deploying the supplemental support structure.

The fistula may optionally be dilated with a PTA catheter before,during, and/or after deploying the prosthesis 620. The diameter of thePTA catheter (e.g., about 3 mm to about 6 mm) may be selected based atleast in part on: the diameter of the artery 600, the diameter of thevein 602, the composition of the interstitial tissue, thecharacteristics of the prosthesis 620, combinations thereof, and thelike.

Once the prosthesis 620 is in place, the prosthesis delivery system maybe removed, as shown in FIG. 26B. An AV fistula is thereby formedbetween the artery 600 and the vein 602. Blood flows through the lumenof the prosthesis 620 even though the prosthesis lacks or is free fromgraft material due to the hemodynamic effects of the low porosity (e.g.,less than about 50% porosity or other values described herein). FIG. 26Bshows an implementation in which the blocking material 608, 610 was notused. Once the prosthesis 620 is in place, valves in the veins may bemade incompetent, for example as described herein.

In embodiments in which the prosthesis 620 comprises two pluralities offilaments that may be deployed separately (e.g., as described withrespect to certain embodiments of FIG. 25B), the pluralities offilaments may be deployed at least partially simultaneously,sequentially deployed without intervening steps, or sequentially withintervening steps such as the PTA steps described herein.

FIG. 27 schematically illustrates another example embodiment of aprosthesis 720 and a method for effecting retroperfusion. Although somedimensions and even an example scale of “10 mm” are provided, theshapes, dimensions, positional relationships, etc. of the featuresillustrated therein may vary. The prosthesis 720 is positioned in anartery 700 including an occlusion 704, in a vein 702, and spanninginterstitial tissue T between the artery 700 and the vein 702. Theprosthesis 720 may be positioned, for example, as described hereinand/or using other methods. In some embodiments, the prosthesis 720 isdelivered through a delivery system having a 5 Fr (1.67 mm) innerdiameter over a guidewire having a 2 Fr (0.67 mm) outer diameter.

In some embodiments, the porosity of the first longitudinal section 722,the second longitudinal section 724, and/or the third longitudinalsection 726, or one or more portions thereof may be between about 0% andabout 50% and ranges therebetween, for example as described herein.Blood flow from the artery 700 may be diverted into the vein 702 throughthe prosthesis 720, for example due to hemodynamic forces such as apressure difference between the artery 700 and the vein 702. The lowporosity of the prosthesis 720 may allow the fluid to flow substantiallythrough the lumen of the prosthesis 720 substantially without perfusingthrough the sidewalls of the prosthesis 720. In some embodiments,proximal and/or distal portions towards the ends of the prosthesis 720may be configured to appose vessel sidewalls, for example having a lowerporosity, since blood is not likely to flow through those portions.

The techniques described herein may be useful for forming a fistulabetween two body cavities near the heart, in the periphery, or even inthe lower extremity such as the plantar arch. FIGS. 28A and 28Bschematically illustrate arteries and veins of the foot, respectively. Afistula or anastomosis may be formed between two blood vessels in thefoot. In one example, a passage from an artery to a vein was formed inthe mid-lateral plantar, from the lateral plantar artery to the lateralplantar vein.

The artery supplying blood to the foot was occluded and the subintimalspace was calcific. A wire was urged distally, and traversed into anadjacent vein. The hole between the artery and the vein was dilated witha 1.5 mm balloon, for example because a small arteriovenous fistulashould not cause much if any damage for the patient at that position andin that position. After dilatation, blood started to flow from theartery to the vein without leakage. After such flow was confirmed,further dilatation of the space was performed using larger balloons (2.0mm, 2.5 mm, 3.0 mm) at larger pressures (e.g., 20-30 atm). Leakage wassurprisingly minimal or non-existent, even without placement of a stent,graft, scaffolding, or other type of device. Procedures not including aprosthesis may reduce costs, procedure time, complexity, combinationsthereof, and/or the like. The lateral plantar vein goes directly intothe vein arch of the forefoot, making it an excellent candidate forsupplying blood to that portion of the foot. The patient had a lot ofpain in the foot prior to the procedure and no pain in the foot afterthe procedure, indicating that blood was able to be supplied through thevein retrograde, as described herein. Fistula or anastomosis maintainingdevices may optionally be omitted for certain situations, such as forhemodialysis in which a distal or lower extremity artery and vein may bedescribed as “glued” in surrounding tissue (e.g., mid-lateral plantarartery and vein)/

In some situations, a fistula or anastomosis maintaining device may beoptionally used. Several fistula maintaining devices are describedherein. FIG. 29 schematically illustrates an example embodiment of ananastomosis device 800. The anastomosis device includes a first section802, a second section 804, and optionally a third section 806longitudinally between the first section 802 and the second section 804.The first section 802 may be configured to anchor in a first body cavity(e.g., blood vessel such as an artery or vein). The first section 802may include expandable members, barbs, etc. The second section 804 maybe configured to anchor in a second body cavity (e.g., blood vessel suchas an artery or vein, which may be the opposite type of the first bodycavity). The third section 806 may be configured to span between thelumens of the first body cavity and the second body cavity. In someembodiments, the space between the lumens of the first body cavity andthe second body cavity generally comprises the vessel walls such thatthe dimensions of the third section 806 may be small or even omitted.

Some anastomosis devices are available and/or have been developed forthe treating holes in larger vessels (e.g., Spyder from Medtronic,CorLink from Johnson and Johnson, Symmetry from St. Jude Medical,PAS-Port from Cardica, and ROX Coupler from ROX Medical). Such devicesmay be appropriate for use in the periphery or the lower extremity, forexample if resized and/or reconfigured. Other devices are also possible.

FIG. 30 schematically illustrates an example embodiment of two bloodvessels 902 and 904 coupled together with an anastomosis device 800spanning the walls of the blood vessels 902, 904. The blood vessel 902is an artery, as schematically shown by having thick walls, and theblood vessel 904 is a vein. Other combinations of blood vessels andother body cavities are also possible. After a passage 906 is formedbetween the first blood vessel 902 and the second blood vessel 904, forexample as described herein (e.g., using a wire, a deployable needle,one or more balloons, etc.), the anastomosis device 800 is deployed. Forexample, the distal end of an anastomosis device 800 deployment systemmay reside in the first blood vessel 902 and extend partially throughthe passage 906. The first section 802 of the anastomosis device 800 maybe deployed through the passage 906 and in the second blood vessel 904.Upon deployment, the first section 802 may self-expand, for example toappose the walls of the second vessel 904. The third section 806 of theanastomosis device 800 may be deployed through the passage 906. Upondeployment, the third section 806 may self-expand, for example to apposethe tissue surrounding the passage 906 and to maintain patency throughthe passage 906. The second section 804 of the anastomosis device 800may be deployed in the first blood vessel 902. Upon deployment, thesecond section 804 may self-expand, for example to appose the walls ofthe first vessel 902. One or more of the first section 802, the secondsection 804, and the third section 806 may be expanded using a balloon.Different balloons or series of balloons can be used for different ofthe sections 802, 804, 806 of the anastomosis device 800.

FIGS. 32A through 32D illustrate an example method and device foridentifying and avoiding a bifurcation 1104 in a percutaneous bypassprocedure. A first vessel 1000 (e.g., an artery) is occluded by anocclusion 1008. The occlusion 1008 may be partial or complete (e.g.,causing critical limb ischemia). A percutaneous procedure, for exampleas described herein, can use a second vessel 1002 (e.g., a vein) tobypass the occlusion 1008. A first catheter 1010 resides in the firstvessel 1000. A second catheter 1020 resides in the second vessel 1002.The second vessel 1002 includes a bifurcation 1004 at a junction with abranch or collateral vessel 1006. The first catheter 1010 comprisesultrasound transmitter 1012 (e.g., a directional transmitter) configuredto send a signal 1014 to an ultrasound receiver 1022 (e.g., anomnidirectional received) of the second catheter 1020 in the secondvessel 1002, for example as described herein. A needle 1016 (FIG. 32D)may extend out of the first catheter 1010 towards the second vessel1002. In the configuration shown in FIG. 32A, if the needle 1016 extendsat the same angle as the signal 1014, for example as described herein(e.g., FIG. 3 ), then the needle 1016 may extend into the bifurcation1004 and into the branch vessel 1006. Subsequent navigation of aguidewire through a lumen of the needle 1016 may disadvantageously beinto the branch vessel 1006 rather than second vessel 1002. Navigationin the branch vessel 1006 rather than the second vessel 1002 may bedifficult to detect by the user.

FIG. 32B illustrates a first step in an example method of diagnosing theexistence and/or location of the bifurcation 1004. The expandable member1024 is expanded, for example by providing fluid flow (e.g., saline,contrast materials, etc.) through an inflation lumen 1026 in fluidcommunication with the expandable member. In FIGS. 32A-32D, the secondcatheter 1020 comprises an integral expandable member 1024 (e.g.,comprising a balloon) and an inflation lumen 1026. A separate cathetercomprising an expandable member may be used in the second vessel 1002.Expansion of the expandable member 1024 occludes the second vessel 1002.As shown by the arrows 1027, blood is still flowing towards theexpandable member 1020 from both from a proximal end of the secondvessel 1002 and from the branch vessel 1006. The occlusion of the secondvessel 1002 and the blood still flowing into the second vessel 1002 cancause the second vessel 1002 to expand. Expansion of the second vessel1002 can make the second vessel easier to target and/or puncture withthe needle 1016.

FIG. 32C shows the introduction of contrast material 1028 in the secondvessel 1002. The contrast material 1028 maybe delivered through aninfusion port integral with the second catheter 1020 and/or using aseparate catheter in the second vessel 1002. The contrast material 1028may comprise, for example contrast agents or contrast media configuredto improve fluoroscopy including iodine-based, barium sulfate-based(e.g., for subjects with impaired kidney function), combinationsthereof, and the like. The contrast material 1028 can contribute toexpansion of the second vessel 1002. The contrast material 1028 flowsuntil reaching the expandable member 1024, then begins to gatherproximate to the expandable member 1024. A portion of the contrastmaterial 1028 may gather in the bifurcation 1004, making the existenceand location of the bifurcation 1004 and/or the branch vessel 1006visible under fluoroscopy. Without the expandable member 1024, thecontrast material 1028 would flow through the second vessel 1002 withoutshowing the bifurcation 1004 and/or the branch vessel 1006. Withknowledge of the angle of the needle 1016, and the position of the firstcatheter 1010, the user can determine whether the needle 1016 wouldextend into the bifurcation 1004 and/or the branch vessel 1006. Sincethis situation would generally result in ineffective bypass, a differentpuncture site for forming a fistula may be selected.

In FIG. 32D, the first catheter 1010 has been retracted by a distance1018. The ultrasound signal 1014 (FIG. 32A) from the first catheter 1010may be used to target the second catheter 1020. The procedure shown inFIGS. 32B and 32C may be repeated, for example looking for anotherbifurcation. Once the user is satisfied with that the needle 1016 willpuncture the second vessel 1002 at a position free from a bifurcation toinhibit or prevent advancement into a branch vessel rather than thesecond vessel 1002, the needle 1016 may be extended from the firstcatheter 1010, out of the first vessel 1000, through interstitial tissuebetween the first vessel 1000 and the second vessel 1002, and into thesecond vessel 1002 at a position at which the second vessel 1002 doesnot include a bifurcation or branch vessel. The needle 1016 may beextended with the expandable member 1024 inflated or deflated, or evenwith the second catheter 1020 removed from the second vessel 1002. Insome embodiments, a permanent occluder may be positioned in the secondvessel 1002, for example as described herein (e.g., FIG. 4 ). Aguidewire may be tracked through a lumen of the needle 1016, and otherprocedures as described herein, for example fistula dilation, deploymentof a fistula prosthesis, deployment of a stent graft, use of a reversevalvulotome, etc., can be performed by tracking a catheter overguidewire (e.g., through the first vessel 1000, through the fistula, andthen through the second vessel 1002). In some embodiments, the devicesand methods described herein can be used to guide a needle into abifurcation and/or a branch vessel if desired by the user.

FIGS. 33A and 33B schematically illustrate an example procedure that canbe performed the following connection of a first vessel 1100 (e.g., anartery) and a second vessel 1102 (e.g., a vein) with a needle 1116traversing interstitial tissue 1101. The needle 1116 extends from afirst catheter 1110 in the first vessel 1100. The first vessel 1100 isoccluded by an occlusion 1108. In FIG. 33A, a guidewire 1118 extendsthrough a lumen in the needle 1116, and can then be navigated throughthe second vessel 1102. The needle 1116 may be retracted upon placementof the guidewire 1118, and the first catheter 1110 may be retracted fromthe first vessel 1100. As illustrated in FIG. 33B, a second catheter1120 maybe tracked over the guidewire 1118 through the first vessel1100, through the interstitial tissue 1101, and into the second vessel1102. In FIG. 33B, the second catheter 1120 comprises a balloon cathetercomprising a balloon 1122 (e.g., a PTA balloon). Inflation of theballoon 1122 can dilate a fistula formed between the first vessel 1100and the second vessel 1102. Dilation of the interstitial tissue 1101and/or aperture in the vessels 1100, 1102 can enhance later procedures,such as placement of a prosthesis across the fistula.

FIGS. 34A through 35F illustrate example procedures that can beperformed when a guidewire 1118 is in a vessel 1102 (e.g., a vein). InFIG. 34A, a prosthesis 1124 has been placed across the interstitialtissue 1101 between the first vessel 1100 in the second vessel 1102. Thedeployment system for placing the prosthesis 1124 may have been trackedover the guidewire 1118. A catheter 1130A is tracked over the guidewire1118 distal to the prosthesis 1124. As shown in FIG. 34B, the catheter1130A may be tracked all the way towards a heel 1103 of the subject.

As shown in FIG. 34C, the catheter 1130A is configured to deliver afirst stent graft 1132A, which can line the second vessel 1102,disabling valves in the second vessel 1102, occluding branch vessels ofthe second vessel 1102, etc., for example as described. In FIG. 34D, thecatheter 1130A has been retracted and another catheter 1130B has beentracked over the guide wire 1118. FIG. 34D also shows an example ofwhere the occlusion 1108 in the first vessel 1100 may terminate, whichmay be useful if another fistula was formed between the first vessel1100 and the second vessel 1102 (e.g., to bypass the occlusion 1108).Forming a second fistula may be the same or different than forming thefirst fistula (e.g., using at least one of the ultrasound guidance,extending a needle, and prosthesis deployment described herein). In FIG.34E, the catheter 1130B is delivering a second stent graft 1132B, whichmay at least partially overlap the first stent graft 1132A in an area1133. In some embodiments, the distal end of the second stent graft1132B may be configured to overlap the proximal end of the first stentgraft 1132A. In some embodiments, the proximal end of the first stentgraft 1132A may be configured to be overlapped by the distal end of thesecond stent graft 1132B. In some embodiments, for example if the secondstent graft 1132B is placed first, the proximal end of the first stentgraft 1132A may be configured to be overlapped by the distal end of thesecond stent graft 1132B. The second stent graft 1132B may belongitudinally spaced from the first stent graft 1132A, for example ifthe longitudinal spacing is small enough that there is unlikely to be abranch vessel and/or a valve in the location of the spacing.

In FIG. 34F, the second stent graft 1132B at least partially overlapsthe prosthesis 1124. In some embodiments, the proximal end of the secondstent graft 1132A may be configured to overlap the distal end of theprosthesis 1124. In some embodiments, the distal end of the prosthesismay be configured to be overlapped by the proximal end of the secondstent graft 1132B. The second stent graft 1132B may be longitudinallyspaced from the prosthesis 1124, for example if the longitudinal spacingis small enough that there is unlikely to be a branch vessel and/or avalve in the location of the spacing. FIG. 34F also shows the catheter1132B retracted out of the vasculature. Although two stent grafts 1132A,1132B are described in this example, one, two, three, or more stentgrafts may be used, for example depending on the length of the secondvessel 1102 distal to the prosthesis 1124, the length(s) of the stentgraft(s), the likelihood or existence of branch vessels, etc.

FIG. 35A shows the second vessel 1102 distal to the first stent graft1132A. The second vessel 1102 comprises a first valve 1105A thatinhibits or prevents blood 1111 from flowing distal to the first valve1105A. In FIG. 35B, a catheter 1140 is tracked over the guidewire 1118towards the first valve 1105A through the stent graft 1132A. Thecatheter 1140 comprises a valve disabling device. In FIG. 35C, thecatheter 1140 is shown as comprising a reverse valvulotome 1142, forexample as described herein, and a sheath 1144. Referring again FIG.35B, when the reverse valvulotome 1142 is in the sheath 1144, thereverse valvulotome 1142 is in a radially contracted state. As shown inthe FIG. 35C, when the sheath 1144 is proximally retracted and/or thereverse valvulotome 1142 is distally advanced, the reverse valvulotome1142 radially expands to a state configured to cut valves upon distaladvancement. In FIG. 35D, the blade or blades of the reverse valvulotome1142 ablate or cut or sever the leaflets of the first valve 1105A,allowing blood 1111 to flow distal to the first valve 1105A.

Referring to FIG. 35E, after the first valve 1105A has been disabled,the reverse valvulotome 1142 may be radially compressed in the outersheath 1144 for further distal advancement without affecting the secondvessel 1102. As shown in FIG. 35F, when a second valve 1105B isencountered, the reverse valvulotome 1142 may extend from the sheath1144 and then distally advanced to disable the second valve 1105B,allowing the blood 1111 to flow distal to the second valve 1105B. Theuse of the reverse valvulotome 1142 may be repeated for as many valvesin the second vessel 1102 as desired by the user. In some embodiments, areverse valvulotome 1142 may be used before placement of stent grafts1132A, 1132B. Valve disabling devices other than a reverse valvulotome,for example but not limited to the two-way valvulotome 1300 as describedherein, may also or alternatively be used.

FIGS. 36A through 36D illustrate method of promoting retroperfusion ofblood through a vein into toes. In FIG. 36A, the vasculature illustratedincludes a lateral plantar vein 1200, a deep plantar venous arch 1202,metatarsal veins 1204, and a medial plantar vein 1206. Blood flowthrough the lateral plantar vein 1200, as illustrated by the arrow 1201,is counter to the normal direction of blood flow, for example due toretroperfusion caused by percutaneous bypass from an artery into a veinupstream of the lateral plantar vein 1200. The blood continues to flowthrough the vasculature as shown by the arrows 1203, where the blood isjoined by blood flowing away from the toes in the normal direction ofblood flow through the metatarsal veins 1204, as indicated by the arrows1205. The medial plantar vein 1206 is configured to return blood towardsthe heart, so normal blood flow, as indicated by the arrow 1207, ismaintained. Blood may preferentially flow as illustrated in FIG. 36A,which is not desirable when the intended effect of the retroperfusion isto perfuse oxygenated blood to the toes.

FIG. 36B illustrates an example embodiment of a device that can be usedto promote blood flow to the toes through the metatarsal veins 1204. Afirst catheter 1210 comprising a first expandable member 1212 (e.g.,balloon) may comprise a 6 French occlusion catheter comprising athree-way fitting. The expandable member 1212 is inflated in the lateralplantar vein 1200. A second catheter 1220 that is coaxial with the firstcatheter 1210 extends through the expandable member 1212, through thedeep plantar venous arch 1202, and into the medial plantar vein 1206.The second catheter 1220 comprises an expandable member 1222 (e.g.,balloon), which may be inflated in the medial plantar vein 1206. At thatpoint, the medial planar vein 1206 is partially or fully occluded, andblood flow through the medial plantar vein 1206 is inhibited orprevented. Blood may continue to flow from the toes through themetatarsal veins 1204, as indicated by the persistence of the arrows1205. The blood has no exit route, so hydrostatic pressure may build upin the deep plantar venous arch 1202, which can disable valves and/orother structures configured to promote normal blood flow. Optionally,the first expandable member 1212 may permit retroperfusion blood toflow, which can further build pressure in the deep plantar venous arch1202. Blood flow would normally perfuse opposite to the direction of theretroperfusion in the lateral plantar vein 1200, but the expandablemember 1212 can inhibit or prevent such flow.

In some embodiments, a device comprising a single catheter may be usedto promote blood flow to the toes through the metatarsal veins 1204. Thedevice may comprise a first expandable member and a second expandablemember. For example, the device can comprise a double balloon catheterhaving a first balloon and a second balloon distal to the first balloon.

The device may allow one of the first and second expandable members toinflate independently of the other expandable member. For example, insome embodiments, the device may comprise at least a first lumen and asecond lumen. The first lumen can be configured to inflate the firstexpandable member independently of the second expandable member. Thesecond lumen can be configured to inflate the second expandable memberindependently of the first expandable member. The device may comprise asingle lumen configured to inflate both the first and second expandablemembers. The device may include one or more inflation ports configuredto inflate at least one of the first and second expandable members.

The device may be configured to adjust the distance between theexpandable members prior to inflation of at least one of the expandablemembers. The device may permit the expandable members to isolate apatient-specific treatment area and promote retroperfusion of bloodthrough a vein into toes, as described herein. For example, the devicemay permit the placement of the first expandable member in the lateralplantar vein 1200 and placement of the second expandable member in themedial plantar vein 1206, and/or vice versa. The device may comprise oneor more handles configured to control the movement of various portionsof the device. For example, the device may comprise a first handle tocontrol the movement of both the first and second expandable members. Insome embodiments, the device may comprise a second handle configured tocontrol the movement of the first expandable member independently of thesecond expandable member. The second handle may allow the device toadvance the first expandable member in a proximal direction relative tothe second expandable member from a first position to a second position.After the first expandable member has been advanced to a secondposition, the second handle may allow the device to advance the firstexpandable member in a distal direction to the first position.

The device may comprise an infusion port configured to inject fluid intoa treatment area defined by the first and second expandable members. Forexample, the treatment area may comprise the deep plantar venous arch1202. After the first and second expandable members have been inflated,blood flow through the medial plantar vein 1206 is inhibited orprevented. The infusion port may then allow the device to inject fluidinto the treatment area. The injection of fluid can increase hydrostaticpressure within the treatment area. The hydrostatic pressure increasesdue to the inflated first and second expandable members preventing theinjected fluid from flowing outside the treatment area through themedial plantar vein 1206 and/or the lateral plantar vein 1200. Theinfusion port can be configured to sufficiently increase in hydrostaticpressure within the treatment area to allow the device to disable valvesand/or other structures. For example, the infusion port may be sized toinject an amount of fluid sufficient to increase the hydrostaticpressure to promote blood flow to the toes.

In FIG. 36C, blood flow is allowed through the expandable member 1212,as shown by the arrow 1201, but the inflatable member 1212 inhibitsnormal blood flow in the deep plantar venous arch 1202. Pressure due tothe restricted flow builds up in the deep plantar venous arch 1202. Thepressure buildup, optionally in combination with the flow of blood fromthe lateral plantar vein 1200, can causes reversal of blood flow intothe metatarsal veins 1204, as shown by the arrows 1209.

In FIG. 36D, the first catheter 1210 and the second catheter 1220 areremoved. The disabling of the normal vasculature in the deep plantarvenous arch 1202 causes continued retroperfusion of blood through themetatarsal veins 1204, as shown by the maintenance of the arrows 1209. Asmall amount of oxygenated blood may flow through the medial plantarvein 1206. In some embodiments, the medial plantar vein 1206 may remainoccluded using the expandable member 1222 (e.g., detachable from thecatheter 1220) or a different occluder. In some embodiments, blood mayflow through the plantar vein 1206 in a direction opposite normal bloodflow.

FIG. 37A illustrates an example of a valve disabling device 1300 in aradially expanded state. The valve disabling device 1300 is configuredto cut or ablate or sever or disable leaflets of a valve (e.g., a venousvalve) upon retraction and/or advancement in a radially expanded state.The valve disabling device 1300 comprises a proximal portion 1308, adistal portion 1306, and intermediate portion 1302 between the proximalportion 1308 and the distal portion 1306. The proximal portion 1308comprises a tubular element. The distal portion 1306 comprises a tubularportion. The device 1300 may be formed by cutting (e.g., laser cutting)a hypotube, cutting a flat sheet and rolling into a hypotube, formingparts of the device 1300 and then coupling the parts together, shapesetting, combinations thereof, and the like. The tubular element of thedistal portion 1306 and/or the tubular element of the proximal portion1308 may comprise an uncut portion of a hypotube or sheet.

The proximal portion 1308 may be coupled to a pusher element 1320. Thepusher element may comprise a lumen, for example configured to advanceacross a guidewire. The device 1300 may be in a radially compressedstate when confined in a sheath 1304 and in a radially expanded statewhen not confined in the sheath 1304. The device 1300 may be radiallyexpanded by proximally retracting the sheath 1304 and/or by distallyadvancing the pusher element 1320 and thereby the device 1300. Thedevice 1300 may be radially compressed by distally advancing the sheath1304 and/or by proximally retracting the pusher element 1320 and therebythe device 1300. In the radially expanded state, the intermediateportion 1302 may radially expand while the proximal portion 1308 and thedistal portion 1306 do not radially expand (e.g., as shown in FIG. 37A).

The intermediate portion 1302 may comprise cut portions of a hypotube orsheet. The intermediate portion 1302 may comprise one or more struts1316 extending between the proximal portion 1308 and the distal portion1306. The intermediate portion 1302 may comprise between about one strutand about eight struts (e.g., one strut, two struts, three struts (e.g.,as shown in FIG. 37A), four struts, five struts, six struts, sevenstruts, eight struts, ranges between such values, etc.). The struts 1316may be approximately equally circumferentially spaced, for example toprovide uniform cutting in any circumferential orientation. For example,three struts 1316 may be circumferentially spaced by about 120°. Thestruts 1316 may unequally circumferentially spaced, for example toprovide more cutting in a certain circumferential area. For example, afirst strut 1316 may be circumferentially spaced from a second strut1316 by about 135° and spaced from a third strut 1316 by about 135°, andthe second strut 1316 may be spaced from the third strut 1316 by about90°.

The strut 1316 may comprise between about one and about four blades(e.g., one blade, two blades (e.g., as shown in FIG. 37A), three blades,four blades, ranges between such values, etc.). The strut 1316 shown inFIG. 37A comprises a first blade 1312 and a second blade 1314. The firstblade 1312 faces proximally and is configured to cut as the device 1300is proximally retracted. The second blade 1314 faces distally and isconfigured to cut as the device 1300 is distally advanced. Theproximally facing blades 1312 and the distally facing blades 1314 allowthe device 1300 to disable a valve when proximally retracted and/or whendistally advanced, providing flexibility as a two-way valvulotome. Otherconfigurations are also possible. For example, a first strut 1316 maycomprise a proximally facing blade 1312 and a second strut 1316 maycomprise a distally facing blade 1314. For another example, a firststrut 1316 may comprise a plurality of proximally facing blades 1312 anda second strut 1316 may comprise a plurality of distally facing blades1314. For another example, a first strut 1316 may comprise a proximallyfacing blade 1312 and a distally facing blade 1314 and a second strut1316 may comprise zero blades or be free of or devoid of blades. Foranother example, a first strut 1316 may comprise a proximally facingblade 1312 and a distally facing blade 1314 and a second strut 1316 maycomprise a distally facing blade 1314. For another example, a firststrut 1316 may comprise two proximally facing blades 1312 and a distallyfacing blade 1314.

FIG. 37B is a flattened side view of the valve disabling device 1300 ofFIG. 37A. The device 1300 may be cut from a flat sheet that is rolledinto a hypotube. FIG. 37B provides an example cut pattern that may beused to form the device 1300. The cut pattern shown in FIG. 37B may alsobe on a round hypotube. FIG. 37B provides some example dimensions of thedevice 1300. The length 1340 of the distal portion 1306 may be betweenabout 0.1 mm and about 3 mm (e.g., about 0.1 mm, about 0.5 mm, about 1mm, about 1.5 mm, about 2 mm, about 3 mm, ranges between such values,etc.). The distal portion 1306 may have a length 1340 configured toprovide a stable joint for the distal ends of the struts 1316. Thecircumferential length 1342 of the distal portion 1306 may be betweenabout 1.5 mm and about 5 mm (e.g., about 1.5 mm, about 2 mm, about 2.5mm, about 3 mm, about 3.5 mm, about 4 mm, about 5 mm, ranges betweensuch values, etc.). The circumferential length 1342 of the distalportion 1306 may correspond to a circumference of a hypotube used toform the disabling device 1300 or an expansion thereof. The length 1344of the space between struts 1316 may be between about 0.1 mm and about 1mm (e.g., about 0.1 mm, about 0.2 mm, about 0.3 mm, about 0.4 mm, about0.5 mm, about 0.7 mm, about 0.8 mm, about 0.9 mm, about 1 mm, rangesbetween such values, etc.). The length 1344 of the space between struts1316 may be between about 2% and about 67% of the circumferential length1340 of the distal portion 1306 (e.g., about 2%, about 5%, about 10%,about 15%, about 20%, about 25%, about 35%, about 50%, about 67%, rangesbetween such values, etc.). The circumferential thickness 1346 of thestruts 1316 maybe between about 0.1 mm and about 1 mm (e.g., about 0.1mm, about 0.2 mm, about 0.3 mm, about 0.4 mm, about 0.5 mm, about 0.7mm, about 0.8 mm, about 0.9 mm, about 1 mm, ranges between such values,etc.). The circumferential thickness 1346 of the struts 1316 may bebetween about 2% and about 67% of the circumferential length 1340 of thedistal portion 1306 (e.g., about 2%, about 5%, about 10%, about 15%,about 20%, about 25%, about 35%, about 50%, about 67%, ranges betweensuch values, etc.). Thicker struts 1316 and/or less spacing between thestruts 1316 may provide more rigidity and cutting than thinner struts1316. Thinner struts 1316 and/or more spacing between the struts 1316may use less force for radial expansion and/or retraction. If the spacesbetween the struts 1316 have rounded proximal edges, the radius ofcurvature 1350 at the interface between the proximal portion 1308 andthe intermediate portion 1302 may be between about 0.1 mm and about 0.5mm (e.g., about 0.1 mm, about 0.2 mm, about 0.3 mm, about 0.4 mm, about0.5 mm, ranges between such values, etc.). If the spaces between thestruts 1316 have rounded distal edges, the radius of curvature at theinterface between the distal portion 1306 in the intermediate portionmay be between about 0.1 mm and about 0.5 mm (e.g., about 0.1 mm, about0.2 mm, about 0.3 mm, about 0.4 mm, about 0.5 mm, ranges between suchvalues, etc.). The radii of curvature at the proximal and distalinterfaces may be the same or different. Rather than a radius ofcurvature, the struts 1316 could meet the proximal portion 1308 and/orthe distal portion 1306 at angle. The length 1348 of the proximalportion 1308 may be between about 0.1 mm and about 8 mm (e.g., about 0.1mm, about 0.5 mm, about 1 mm, about 2 mm, about 3 mm, about 4 mm, about5 mm, about 6 mm, about 8 mm, ranges between such values, etc.). Theproximal portion 1308 may have a length 1348 configured to provide astable joint for the proximal ends of the struts 1316. The proximalportion 1308 may have a length 1348 configured to be coupled to thepusher element 1320. The circumferential length of the proximal portion1308 may correspond to a circumference of a hypotube used to form thedisabling device 1300 or an expansion thereof. The circumferentiallength of the proximal portion 1308 may be the same or different thenthe circumferential length 1342 of the distal portion 1306. For example,if the device 1300 is cut from a hypotube and the proximal portion 1308and the distal portion 1306 comprise uncut portions of the hypotube, theproximal portion 1308 and the distal portion 1306 may have the samecircumferential length, or one may be expanded relative to the other(e.g., due to a shape setting process, expansion by outward force of apusher element 1320, etc.).

FIG. 37C is an expanded view of the flattened side view of the valvedisabling device 1300 of FIG. 37A in the area identified by the circle37C in FIG. 37B. FIG. 37C shows some example dimensions of the device1300. The radius of curvature 1356 of the blade 1314 may be betweenabout 0.1 mm and about 1 mm (e.g., about 0.1 mm, about 0.2 mm, about 0.3mm, about 0.4 mm, about 0.5 mm, about 0.7 mm, about 0.8 mm, about 0.9mm, about 1 mm, ranges between such values, etc.). The distance 1358between an edge of the blade 1314 and a strut 1316 may be between about0.1 mm and about 2 mm (e.g., about 0.1 mm, about 0.25 mm, about 0.5 mm,about 0.75 mm, about 1 mm, about 1.25 mm, about 1.5 mm, ranges betweensuch values, etc.). The combined thickness 1360 of a strut 1316 andblade may be between about 0.1 mm and about 3 mm (e.g., about 0.1 mm,about 0.5 mm, about 1 mm, about 1.5 mm, about 2 mm, about 3 mm, rangesbetween such values, etc.). The dimensions of the blade 1312 on thestrut 1316 of FIG. 37C maybe the same or different than the dimensionsof the blade 1314 in FIG. 37C. The dimensions of the other blades 1314may be the same or different than the dimensions of the blade 1314 inFIG. 37C.

FIG. 37D is an end view of the valve disabling device 1300 of FIG. 37Aflattened as shown in FIG. 37B. FIG. 37D shows some example dimensionsof the device 1300. The thickness 1362 may be between about 0.05 mm andabout 0.25 mm (e.g., about 0.05 mm, about 0.1 mm, about 0.15 mm, about0.2 mm, about 0.25 mm, ranges between such values, etc.). A greaterthickness 1362 may provide more rigidity and cutting force. A smallerthickness 1362 may use less force for radial expansion and/orretraction. If the device 1300 is formed from a hypotube, the thickness1362 maybe a difference between an inner diameter of the hypotube and anouter diameter of the hypotube, or the thickness of the hypotube wall.The circumferential distance 1342, as described above, may be about 1.5mm and about 5 mm (e.g., about 1.5 mm, about 2 mm, about 2.5 mm, about 3mm, about 3.5 mm, about 4 mm, about 5 mm, ranges between such values,etc.).

FIG. 37E is an end view of the valve disabling device 1300 of FIG. 37Ain a radially contracted state. FIG. 37 shows some example dimensions ofthe device 1300 in a radially contracted state. The outer diameter 1352may be between 0.6 mm and about 1.5 mm (e.g., about 0.6 mm, about 0.8mm, about 1 mm, about 1.2 mm, about 1.5 mm, ranges between such values,etc.). The outer diameter 1352 is greater than the inner diameter 1354.The inner diameter 1354 may be between about 0.5 mm and about 1.4 mm(e.g., about 0.5 mm, about 0.75 mm, about 1 mm, about 1.25 mm, about 1.4mm, ranges between such values, etc.). Referring again to FIG. 37D, thethickness 1362 may correspond to the difference between the outerdiameter 1352 and the inner diameter 1354, divided by two. For example,if the outer diameter 1352 is 1 mm and the inner diameter 1354 is 0.8mm, the thickness 1362 would be: (1 mm-0.8 mm)/2=0.1 mm.

FIG. 37F is a side view of the valve disabling device 1300 of FIG. 37Ain a radially contracted state. FIG. 37G is another side view of thevalve disabling device 1300 of FIG. 37A in a radially contracted stateand circumferentially rotated compared to FIG. 37F. FIGS. 37F and 37Gshow some example dimensions of the device 1300 in a radially contractedstate. The length 1364 between a distal end of the distal portion 1306and a proximal end of the proximal portion 1308 may be between about 15mm and about 27 mm (e.g., about 15 mm, about 18 mm, about 21 mm, about24 mm, about 27 mm, ranges between such values, etc.). Referring againto FIG. 37B, the length 1340 of the distal portion 1306 and the length1348 of the proximal portion 1308 may be subtracted from the length 1364to calculate the length of the intermediate portion 1302. The length1366 between an edge of the blade 1314 and a distal end of the proximalportion 1308 may be between about 5 mm and about 10 mm (e.g., about 5mm, about 6 mm, about 7 mm, about 8 mm, about 9 mm, about 10 mm, rangesbetween such values, etc.). The length 1366 may affect and/or be basedon a diameter of the blade 1314 in a radially expanded state.

FIG. 37H is a side view of the valve disabling device 1300 of FIG. 37Ain a radially expanded state. FIG. 371 is another side view of the valvedisabling device 1300 of FIG. 37A in a radially expanded state andcircumferentially rotated compared to FIG. 37H. FIGS. 37H and 37G showsome example dimensions of the device 1300 in a radially expanded state.The radially expanded state shown in FIGS. 37H and 37G may be fullyexpanded (e.g., the shape of the device 1300 absent external forces) ora partially radially expanded state. The length or radius 1368 between alongitudinal axis 1367 through a center of the device 1300 and outercircumference of an expanded intermediate portion 1302 may be betweenabout 0.5 mm and about 7 mm (e.g., about 0.5 mm, about 1 mm, about 1.5mm, about 2 mm, about 2.5 mm, about 3 mm, about 4 mm, about 5 mm, about6 mm, about 7 mm, ranges between such values, etc.). A length 1370between a distal end of the distal portion 1306 and a proximal end ofthe proximal portion 1308 may be between 10 mm and about 25 mm (e.g.,about 10 mm, about 15 mm, about 18 mm, about 20 mm, about 22 mm, about25 mm, ranges between such values, etc.). Referring again to FIG. 37F,the length 1364 in a radially contracted state may be longer than thelength 1370 in the radially expanded state. The difference between thelength 1370 and the length 1364 may be between about 0.1 mm and about 1mm (e.g., about 0.1 mm, about 0.2 mm, about 0.3 mm, about 0.4 mm, about0.5 mm, about 0.6 mm, about 0.7 mm, about 0.8 mm, about 0.9 mm, about 1mm, ranges between such values, etc.). Referring again to FIG. 37B, thelength 1340 of the distal portion 1306 and the length 1348 of theproximal portion 1308 maybe subtracted from the length 1370 to calculatethe length of the intermediate portion 1302 in a really expanded state.The length 1372 between a tip of a first blade 1314 and a second blade1314, taken transverse to the longitudinal axis 1367 of the device 1300,may be between about 2 mm and about 4 mm (e.g., about 2 mm, about 2.5mm, about 3 mm, about 3.5 mm, about 4 mm, ranges between such values,etc.).

FIG. 37J is a cross-sectional end view of the valve disabling device1300 of FIG. 37A in a radially expanded state taken along the line37J-37J of FIG. 37H. FIG. 37J shows that the blades 1314 maybe rotatedrelative to the struts 1316, as indicated by the arrows 1321. Each blade1314 may be rotated the same amount and in the same direction, ordifferent blades 1314 may be rotated in different amounts and/or indifferent directions. The blades 1312 may also be rotated the same wayand/or in a different way (e.g., opposite) than as shown for the blades1314 in FIG. 37J.

FIGS. 37Ki through 37Nii illustrate example procedures that can beperformed using the valve disabling device 1300 of FIG. 37A. Theprocedures are not mutually exclusive and maybe performed based on, forexample, user preference, anatomy, vessel access point, otherprocedure(s) being performed, combinations thereof, and the like.

FIG. 37Ki shows a device 1300 being tracked through a vessel 1301 havinga valve 1305. The device 1300 may be tracked over a guidewire 1318 thathas been navigated through the valve 1305. The device 1300 may beadvanced over the guidewire 1318 in a radially contracted state, withthe intermediate portion 1302 collapsed in the sheath 1304. In FIG.37Kii, the sheath 1304 is retracted, as indicated by the arrow 1323,which allows the intermediate portion 1302 to radially expand, as shownby the arrows 1325. The device 1300 may then be distantly advanced, asshown by the arrow 1327. The distally facing blades 1314 may interactwith the valve 1305 to cut or ablate or disable the leaflets of thevalve 1305. The intermediate portion 1302 may be really compressed byproximally retracting the device 1300 into the sheath 1304 and/or bydistally advancing the sheath 1304 over the device 1300. The device 1300may then be used to disable another valve or withdrawn as desired.

FIG. 37Li shows a device 1300 tracked through the cavity a vessel 1301including a valve 1305. The device 1300 has been advanced distal to thevalve 1305 in a radially contracted state over the guidewire 1318. InFIG. 37Lii, the sheath 1304 is proximally retracted, as indicated by thearrow 1323, which allows the intermediate portion 1302 of the device1300 to radially expand, as shown by the arrows 1325. The device 1300may then be proximally retracted, as shown by the arrow 1329, whichallows the proximally facing blade 1312 to disable the valve 1305. Theintermediate portion 1302 may be really compressed by proximallyretracting the device 1300 into the sheath 1304 and/or by distallyadvancing the sheath 1304 over the device 1300. The device 1300 may thenbe used to disable another valve or withdrawn as desired.

FIG. 37Mi shows a device 1300 being tracked through a vessel 1301 havinga valve 1305. The device 1300 may be tracked over a guidewire 1318 thathas been navigated through the valve 1305. The device 1300 may beadvanced over the guidewire 1318 in a radially contracted state, withthe intermediate portion 1302 collapsed in the sheath 1304. In FIG.37Mii, the sheath 1304 is retracted, as indicated by the arrow 1323,which allows the intermediate portion 1302 to radially expand, as shownby the arrows 1325. The device 1300 may then be distantly advanced, asshown by the arrow 1327. The distally facing blades 1314 may interactwith the valve 1305 to cut or ablate or disable the leaflets of thevalve 1305. The intermediate portion 1302 may be really compressed byproximally retracting the device 1300 into the sheath 1304 and/or bydistally advancing the sheath 1304 over the device 1300. The device 1300may then be used to disable another valve or withdrawn as desired.Compared to FIGS. 37Ki and 37Kii, the method shown in FIGS. 37Mi and37Mii is from an opposite direction. One direction may be upstream andthe other direction may be downstream. One direction may be in thedirection of normal blood flow and the other direction may be thedirection of blood flow after retroperfusion.

FIG. 37Ni shows a device 1300 tracked through the cavity a vessel 1301including a valve 1305. The device 1300 has been advanced distal to thevalve 1305 in a radially contracted state over the guidewire 1318. InFIG. 37Nii, the sheath 1304 is proximally retracted, as indicated by thearrow 1323, which allows the intermediate portion 1302 of the device1300 to radially expand, as shown by the arrows 1325. The device 1300may then be proximally retracted, as shown by the arrow 1329, whichallows the proximally facing blade 1312 to disable the valve 1305. Theintermediate portion 1302 may be really compressed by proximallyretracting the device 1300 into the sheath 1304 and/or by distallyadvancing the sheath 1304 over the device 1300. The device 1300 may thenbe used to disable another valve or withdrawn as desired. Compared toFIGS. 37Li and 37Lii, the method shown in FIGS. 37Ni and 37Nii is froman opposite direction. One direction may be upstream and the otherdirection may be downstream. One direction may be in the direction ofnormal blood flow and the other direction may be the direction of bloodflow after retroperfusion.

FIG. 38A schematically illustrates an example of a distal end of acatheter 1400. The catheter 1400 may include an ultrasound transducer orother targeting device. The catheter 1400 may be used in a second vessel(e.g. a vein) that can be targeted by another catheter (e.g., comprisingan ultrasound transducer) in a first vessel. The distal end of thecatheter 1400 comprises a capture element 1404 having a funnel shapeextending distal to a tubular element 1402. The capture element 1404 mayextend out the tubular element 1402, for example due to an actuationmechanism coupled to the handle and the capture element 1404, bycomprising shape memory material configured to assume a predeterminedshape upon undergoing a phase change due to temperature (e.g., due tobody temperature versus room temperature), due to expansion by anexpandable member (e.g., an inflatable balloon), and/or othermechanisms. The capture element 1404 may have an angle between about 90°and about 170° (e.g., about 90°, about 110°, about 130°, about 150°,about 170°, ranges between such values, etc.). The tubular member 1402may comprise a lumen 1408 extending at least partially therethrough forguiding a guidewire captured by the capture element 1404 through thecatheter 1400. Guiding a guidewire through the catheter 1400 can ensurethat the guidewire is advanced through the same vessel(s) as thecatheter 1400, rather than through unintended branch or collateralvessels. The lumen 1408 may comprise an expanded portion 1409 that isinternal to the tubular member 1402.

FIGS. 38B through 38D illustrate an example procedure that can beperformed using the distal end of the catheter 1400 of FIG. 38A. FIG.38B is similar to FIG. 32D in that a needle 1016 has passed from a firstvessel 1000, through interstitial tissue, and into a second vessel 1002.The catheter 1400 of FIG. 38A is in the second vessel 1002. The catheter1400 may have been proximally retracted, for example as indicated by thearrow 1403, after being successfully targeted by the catheter 1010 inthe first vessel 1000. The distance of retraction of the catheter 1400after successful targeting may be predetermined (e.g., based on adistance between the distal end of the catheter 1400 and a transducer ofthe catheter 1400) and/or maybe based on user experience, fluoroscopy,combinations thereof, and the like. In FIG. 38C, the capture element1404 has expanded out of the distal end of the catheter 1400. Thecapture element 1404 can act as a funnel to guide a guidewire extendingout of the needle 1016 into the catheter 1400. In FIG. 38D, a guidewire1406 extends out of the needle 1016, for example as described herein, iscaptured by the capture element 1404, and then is guided by the portion1409 into the lumen 1408. The guidewire 1406, further distally advanced,will extend further into the lumen 1408, as opposed to any chance of theguidewire 1406 extending through the branch vessel 1006 and/or otherbranch vessels. Procedures performed by tracking over the guidewire 1406(e.g., valve disabling, graft placement, balloon expansion, etc.), canensure that such procedure will be performed in the intended vessels,which can provide better and more predictable retroperfusion.

FIGS. 38Ei and 38Eii illustrate an example of a distal end of a catheter1440. The catheter 1440 may be similar to the catheter 1400. Thecatheter 1440 includes an inflation lumen 1445 and an expandable member1446 (e.g., comprising a balloon). When the catheter 1440 is it anappropriate position, for example as illustrated in FIG. 38B, anexpandable member 1444 may be expanded, and the capture element 1444 maybe expanded by the expandable member 1446. Compared to FIG. 38Ei, FIG.38Eii shows the expandable member 1446 slightly distally advanced andthen in expanded in order to push the capture element 1444 radiallyoutward. The expandable member 1446 may be positioned and/or shaped toexpand the capture element 1444 without being distally advanced. Asdescribed above, other methods of expanding a capture element 1444 arealso possible.

FIG. 38F illustrates an example of a portion of a catheter 1420. Thecatheter 1420 comprises an ultrasound transducer 1422. The catheter 1420comprises a capture element 1424 that extends out a side of the catheter1420. The capture element 1424 may comprise a funnel leading to a lumen1428, which may optionally comprise an expanded portion 1429. Thecapture element 1424 is configured to capture a guidewire 1406 and guidethe guidewire 1406 into the lumen 1428. The capture element 1424 may belocated proximate to the transducer 1422. In accordance with certaintargeting systems described herein, the needle 1016 may extend towardsthe transducer 1422 such that the guidewire 1406 extending out of theneedle 1016 would be proximate to the transducer 1422, and thusproximate to the capture element 1424. The capture element 1424 may beproximal to the transducer 1422.

FIG. 38G illustrates another example of a portion of a catheter 1430.The catheter 1430 comprises a transducer 1422. The catheter 1430comprises a capture element 1434 that extends out a side of the catheter1430. The capture element 1434 may comprise a partial funnel leading toa lumen 1438, which may optionally comprise an expanded portion 1439.The capture element 1434 may extend partially or fully around acircumference of the catheter 1430. The capture element 1434 isconfigured to guide a guidewire 1406 into a lumen 1438, which mayinclude an expanded portion 1439. The capture element 1434 may comprise,for example, a portion of the catheter 1430 that is deformed uponreaching body temperature to open an aperture to lumen 1438 as thecapture element 1434 expands. The capture element 1434 may be configuredto appose a sidewall of a vessel in which the catheter 1430 resides. Thefeatures of the catheters 1400, 1420, 1430, 1440 may be combined withthe features of the catheter 1020 or other catheters described herein.

FIG. 39A is a perspective view of an example of a portion of a targetcatheter 1500. The target catheter 1500 comprises a sheath 1502 and anexpandable structure 1504. The expandable structure 1504 comprises acollapsed state and an expanded state. FIG. 39A shows the expandablestructure 1504 in the expanded state. The expandable structure 1504comprises a plurality of struts that taper towards the proximal end 1506in the expanded state. The struts form a plurality of cells. In someexamples, a guidewire sheath 1508 extends through the sheath 1502 andthe expandable structure 1504. The target catheter 1500 may be trackedover a first guidewire extending through the guidewire sheath 1508.

FIG. 39B is a side view of the target catheter 1500 of FIG. 39A in afirst state. The first state may be considered a closed state or adelivery state. In the first state, the expandable structure 1504 is inthe collapsed state in the sheath 1502. In some examples, the guidewiresheath 1508 protrudes out of the distal end of the sheath 1502. Aproximal end of the target catheter may include flush ports, guidewireports, and/or the like. A distal end of the catheter may include atargeting sensor (e.g., an ultrasound receiver), a diagnostic sensor(e.g., a pressure sensor), combinations thereof, and/or the like. Insome examples, a targeting sensor is proximal to the expandablestructure 1504 in the collapsed state and/or in the expanded state. Insome examples, a targeting sensor is distal to the expandable structure1504 in the collapsed state and/or in the expanded state. In someexamples, a targeting sensor is longitudinally between a proximal end ofthe expandable structure 1504 and a distal end of the expandablestructure 1504 in the collapsed state and/or in the expanded state.

FIG. 39C is a side view of the target catheter 1500 of FIG. 39A in asecond state. The second state may be considered an open state or adeployed state. The expandable structure 1504 can be deployed from thesheath 1502 by distally advancing the expandable structure 1504 and/orproximally retracting the sheath 1502. FIG. 39C shows the relativemovement between the sheath 1502 and the expandable structure 1504 bythe arrow 1510 and the corresponding radial expansion of the expandablestructure 1504 by the arrows 1512. In some examples, the expandablestructure 1504 is self-expanding (e.g., comprising a shape-memorymaterial such as nitinol) and is able to assume the expanded state whennot confined by the sheath 1502. The expandable structure 1504 can beretrieved in the sheath 1502 by distally advancing the sheath 1502and/or proximally retracting the expandable structure 1504.

FIGS. 39D-39I schematically illustrate an example method of using thetarget catheter 1500 of FIG. 39A. In FIG. 39D, a first catheter 1010 isadvanced in a first vessel 1000 comprising an occlusion, for example asdescribed herein. The target catheter 1500 is advanced in a secondvessel 1002. For example, the target catheter may be tracked over afirst guidewire that has been advanced through the second vessel 1002.The distal end of the sheath 1502 may be longitudinally proximate to theocclusion. In FIG. 39E, the expandable structure 1504 is radiallyexpanded, as shown by the arrows 1514. In some examples, expansion ofthe expandable structure 1504 radially expands the vessel 1002, as shownby the arrows 1516. Expanding the vessel 1002 can increase the targetfor a needle extending from the first catheter 1010. In some examples inwhich the second vessel 1002 is a vein, expanding the vessel 1002 cankeep the vein open, which can avoid influence of potential or eventualspasm.

In FIG. 39F, a needle 1016 extends from the first catheter 1010 out ofthe first vessel 1000, through interstitial tissue, and into the secondvessel 1002. In the second vessel 1002, the needle 1016 extends betweenthe proximal end of the expandable structure 1504 and the distal end ofthe expandable structure 1504. The needle 1016 may extend through a cellof the expandable structure 1504. If the needle 1016 initially contactsa strut of the expandable structure 1504, the strut may be deflectedsuch that the needle 1016 extends through a cell. The tip of the needle1016 does not necessarily need to pierce the center of the second vessel1010 because, even if the second vessel 1002 is pierced at an angle, theneedle 1016 can extend into the expandable structure 1504 at an angle,and a subsequently deployed second guidewire 1406 can be snared by theexpandable structure 1504. The extension of the needle 1016 may beguided using a targeting system (e.g., a directional ultrasoundtargeting system, for example as described herein). In some examples,the needle may be extended towards the expandable structure 1504, forexample using fluoroscopy with or without a targeting system. In certainsuch examples, the expandable structure 1504 may comprise radiopaquemarkers and/or the material of the expandable structure 1504 may beradiopaque (e.g., the expandable structure may comprise radiopaque fluidin an expanded (e.g., inflated) stated).

In FIG. 39G, a second guidewire 1406 is advanced through the firstcatheter 1010 and the needle 1016 into the second vessel 1002. Becausethe needle 1016 extends into the expandable structure 1504, the secondguidewire 1406 extends into the expandable structure 1504. In FIG. 39H,the expandable structure 1504 is collapsed, for example by at leastpartially retracting the expandable structure 1504 into the sheath 1502.Collapsing the expandable structure 1504 grabs or snares the secondguidewire 1406. In some examples, the expandable structure 1504 mayoptionally be twisted or torqued to help snare the second guidewire1406. In FIG. 391 , the target catheter 1500 is proximally retracted.Because the second guidewire 1406 is snared by the expandable structure1504, the second guidewire 1406 is advanced through the second vessel1002, for example during removing the target catheter 1500 from thesecond vessel 1002. Catheters comprising a valvulotome, a stent-graft,and the like may be tracked over the second guidewire 1406 and throughthe second vessel 1002, for example as described herein.

FIG. 40A is a perspective view of an example handle 1600 for deploying atubular structure. The tubular structure may comprise a stent such asthe stent 1122 or a stent-graft such as the stent-graft 1132. In someexamples, the handle 1600 may be used to deploy a valvulotome such asthe valvulotome 1142, 1300, an expandable structure such as theexpandable structure 1504, and the like. The handle 1600 comprises abody 1602 and a knob 1604. The body 1602 comprises a first segment 1606comprising threads 1607. The body 1602 comprises a second segment 1608free of threads. A slot 1609 extends from a proximal part of the body1602 to a distal part of the body 1602.

FIG. 40B is an expanded perspective cross-sectional view of a portion ofthe handle 1600 of FIG. 40A. The knob 1604 comprises threads 1617configured to interact with the threads 1607. A slider 1610 extendsthrough the slot 1609. The slider 1610 comprises a connector 1612coupled to an external sheath such that proximal movement of the slider1610 proximally retracts the external sheath. As the knob 1604 isrotated, the slider 1610 is proximally retracted, which proximallyretracts the external sheath. The initial deployment of a tubularstructure may need a higher quantity of force than later deploymentbecause friction between the tubular structure and the external sheathdecreases as the tubular structure is deployed from the external sheath.The threads 1607, 1617 can help to transmit higher force by convertingrotational force into longitudinal force. Once the knob 1604 isretracted proximal to the threads 1607, the knob 1604 may be proximallypulled, pulling the slider 1610 and thus the external sheath. In someexamples, the initial amount of force would be very difficult to effectby proximal pulling but can be accomplished by rotation of the knob1604. In some examples, rotating the knob 1604 deploys a first amount ofthe tubular structure and sliding the knob 1604 deploys a second amountof the tubular structure. The first and second amounts total the entiretubular structure. In some examples, the first amount is less than thesecond amount. For example, the first amount may be between about 10%and about 60% of the second amount (e.g., about 10%, about 20%, about30%, about 40%, about 50%, about 60%, ranges between such values, andthe like).

In some examples, the transition between the first amount and the secondamount corresponds to approximately a peak deployment force. The peakdeployment force can vary based on, for example, tubular structuredesign (e.g., length, diameter, radial force, material(s)), outer sheathdesign (e.g., diameter, material(s), coating(s)), combinations thereof,and the like. In some examples, the transition is at least about onethird of the length of the tubular structure. In some examples, thetransition is at least about one half of the length of the tubularstructure. In some examples, a ratio between the first amount and thesecond amount can be adjusted by adjusting the threads (e.g., lengthand/or pitch).

FIG. 40C is a perspective view of the handle 1600 of FIG. 40A in adeployed state. FIG. 40D is an expanded perspective cross-sectional viewof a portion of the handle 1600 of FIG. 40A in a deployed state. Theknob 1604 has been rotated and then proximally retracted. Distal to thehandle 1600, a tubular structure is deployed. For example, a stent maybe deployed from a first vessel, through interstitial tissue, and into asecond vessel.

FIG. 41A is a perspective view of an example handle 1700 for deploying atubular structure. The tubular structure may comprise a stent such asthe stent 1122 or a stent-graft such as the stent-graft 1132. In someexamples, the handle 1700 may be used to deploy a valvulotome such asthe valvulotome 1142, 1300, an expandable structure such as theexpandable structure 1504, and the like. The handle 1700 comprises abody 1702 and a knob 1704. The body 1702 optionally includes a shell1716. A slot 1709 extends from a proximal part of the body 1702 to adistal part of the body 1702.

FIG. 41B is an expanded perspective partially transparent view of aportion of the handle 1700 of FIG. 41A. FIG. 41B shows the handle 1700from an opposite side compared to FIG. 41A. The knob 1704 is coupled toa gear or worm gear or worm wheel 1706 having teeth 1717 configured tointeract with teeth 1707 of a slider member or worm or worm screw 1710.The body 1702 is fixably coupled to an inner shaft assembly. The slidermember 1710 if fixably coupled to an outer sheath. In some examples, theinner shaft assembly has a distal end comprising a plurality ofradiopaque marker bands which can make a tubular structure pocketvisible. A proximal radiopaque marker fixed to the inner shaft assemblycan act as a pusher to maintain the longitudinal position of the tubularstructure while an outer sheath is proximally retracted. Movement of theslider member 1710 relative to the body 1702 causes movement of theouter sheath relative to the inner shaft assembly. The slider 1710comprises a first portion 1712, a second portion 1713, and a thirdportion 1714. The first portion 1712 is fixably coupled to an outersheath. The first portion 1712 is inside the body 1702. The secondportion 1713 protrudes through the slot 1709. The third portion 1714 iswider than the second portion 1713. The third portion 1714 is outsidethe body 1702, except in examples including a shell 1716. The userinteracts with the third portion 1714 once the slider member 1710 is inposition to be proximally pulled. The body 1702 may include two slots1709, for example circumferentially opposite each other. In certain suchexamples, the slider member 1710 may include two second portions 1713and two third portions 1714 (e.g., as illustrated in FIG. 41B). Twothird portions 1714 may allow a user to grip both sides of the slidermember 1710, providing grip that is better than one side. In someexamples, the third portion(s) 1714 may comprise features to enhancegrip (e.g., textured surfaces, recesses, flanges, etc.).

FIGS. 41C to 41Eiii show an example method of operating the handle 1700of FIG. 41A. In FIG. 41C, rotation of the knob 1704 causes the gear1706, including the teeth 1717, to rotate. The teeth 1717 interact withthe teeth 1707 of the slider 1710 to convert the rotational force intolongitudinal force, proximally retracting the slider member 1710, whichproximally retracts an external sheath. The initial deployment of atubular structure may need a higher quantity of force than laterdeployment because friction between the tubular structure and theexternal sheath decreases as the tubular structure is deployed from theexternal sheath. The shell 1716 may inhibit a user from attempting toproximally retract the slider member 1710 until an amount of the tubularstructure is deployed that deploying the remaining amount of the tubularstructure does not require a high amount of force. The shell 1716includes a proximal aperture 1718 that the slider can exit upon proximalretraction.

In FIG. 41Di, the knob 1704 has been rotated until the slider member1710 is in a proximal position out of the shell 1716. The exposed slidermember 1710 may be proximally pulled, thereby pulling the outer sheath.In some examples, the initial amount of force would be very difficult toeffect by proximal pulling but can be accomplished by rotation of theknob 1704. FIG. 41Dii shows an example tubular structure 1720 beingdeployed from an example outer sheath 1722. FIG. 41Dii shows thepositions of the tubular structure 1720 and the outer sheath 1722 afterthe knob 1704 has been rotated until the slider member 1710 is in aposition to be proximally retracted (e.g., out of the shell 1716). Afirst portion 1724 of the tubular structure 1720 has been deployed fromthe outer sheath 1722.

FIG. 41Ei is a perspective view the handle 1700 of FIG. 41A in aretracted position. FIG. 41Eii is a perspective cross-sectional view thehandle 1700 of FIG. 41A in a retracted position. The slider member 1710has been proximally retracted to a distal part of the body 1702,proximally retracting the outer sheath by a quantity sufficient todeploy an entire tubular structure. FIG. 41Eiii shows the positions ofthe tubular structure 1720 and the outer sheath 1722 after the slidermember 1710 has been proximally retracted to the distal part of the body1702. A second portion 1726 of the tubular structure 1720 has beendeployed from the outer sheath 1722. The first portion 1724 and thesecond portion 1726 may be an entire length of the tubular structure1720.

In some examples, rotating the knob 1704 deploys a first amount of thetubular structure and sliding the slider member 1710 deploys a secondamount of the tubular structure. The first and second amounts may totalthe entire tubular structure. In some embodiments, first and secondamounts plus a third amount, a fourth amount, etc. may total the entiretubular structure. The third amount, fourth amount, etc. optionally maybe deployed using other features. In some examples, the first amount isless than the second amount. For example, the first amount may bebetween about 10% and about 70% of the second amount (e.g., about 10%,about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, rangesbetween such values, and the like). In some examples, a ratio of thefirst amount to the second amount is between about 1:5 and about 5:3(e.g., about 1:5, about 2:5, about 3:5, about 4:5, about 5:5, about 5:4,about 5:3, ranges between such values, and the like).

With the tubular structure deployed, a catheter coupled to the handle1700 may be removed from the subject. In some examples in which thetubular structure is coupled to a distal end of the inner shaftassembly, the slider member 1710 may be distally advanced to capture afirst portion of the tubular structure. In some examples, capturing thefirst portion of the tubular structure is an amount that is sufficientto safely remove a catheter coupled to the handle 1700 from the subject.In some examples, the knob 1704 may then be rotated to capture a secondportion of the tubular structure.

FIG. 42A is a top view of an example embodiment of a launching device4200. The launching device 4200 includes a proximal portion 4202 and adistal portion 4204. The distal portion 4204 comprises a catheter 4206.The catheter may have an outer diameter, for example, between about 3 Frand about 10 Fr (e.g., about 3 Fr, about 4 Fr, about 5 Fr, about 6 Fr,about 7 Fr, about 8 Fr, about 9 Fr, about 10 Fr, ranges between suchvalues, and the like). The catheter 4206 includes a needle lumen 4208. Aneedle 4216 is configured to extend out of the needle lumen 4208. Theproximal portion 4202 includes a handle 4211 and an actuator 4212. Whenthe actuator 4212 is distally advanced and/or the handle 4211 isproximally retracted, the needle 4216 extends out of the needle aperture4208, for example as described herein with respect to the needle 4216.When the actuator 4212 is proximally retracted and/or the handle 4211 isdistally advanced, the needle 4216 retracts back into the needleaperture 4208. Other types of handles or proximal components are alsopossible. For example, the proximal portion 4202 could comprise anactivator switch, lever, knob, etc. such that when the activator isactuated. For another example, the proximal portion 4202 could comprisetelescoping elements (e.g., proximal portions of catheters or memberscoupled thereto) graspable by a user such that the needle 4216 extendsout of the needle aperture 4208 upon relative longitudinal movementbetween the telescoping elements.

The distal portion 4204 comprises a radiopaque marker 4210. Theradiopaque marker 4210 comprises a radiopaque material (e.g., tantalum,titanium, nickel, tungsten, platinum, gold, silver, iridium, palladium,tin, zirconium, rhenium, bismuth, molybdenum, barium sulfate, tungstenpowder, bismuth subcarbonate, bismuth oxychloride, iodine containingagents such as iohexol (e.g., Omnipaque®, available from AmershamHealth, a division of GE Healthcare), combinations thereof, and thelike).

FIG. 42B is a schematic top, side, and distal end perspective view of adistal portion 4204 of the launching device 4200 of FIG. 42A. Theradiopaque marker 4210 comprises a flat rectangular (e.g., square)marker. The radiopaque marker 4210 does not conform to the arcuate outersurface of the catheter 4206. The radiopaque marker 4210 may berectangular, which can include rectangle, square, having adjacent sidesthat are about 90° to each other, having at least two opposing sidesthat are substantially parallel to each other (e.g., parallelogram,trapezoid), and/or the like, whether having sharp or rounded corners.Shapes other than rectangular are also possible, but the radiopaquemarker 4210 is preferably thin and flat. The radiopaque marker 4210 maybe flat, which can include having a thickness less than a certainamount, for example as described herein. The thickness can be between ahighest point and a lowest point when the radiopaque marker 4210 ispositioned on a flat surface (e.g., a rounded (e.g., following a contourof an outer surface of a catheter) radiopaque marker would have a highercenter point than edge points and should not be considered flat). A flatradiopaque marker 4210 may have a ratio of a thickness to a shortestlateral length between about 1/3,000 and about ⅓ (e.g., about 1/3,000,about 1/2,000, about 1/1,000, about 1/500, about 1/250, about 1/200,about 1/100, about 1/50, about 1/25, about 1/12, about 1/10, about ⅕,about ¼, about ⅓, ranges between such values, and the like). A flatradiopaque marker 4210 may have a ratio of a thickness to a longestlateral length between about 1/3,000 and about ⅓ (e.g., about 1/3,000,about 1/2,000, about 1/1,000, about 1/500, about 1/250, about 1/200,about 1/150, about 1/100, about 1/50, about 1/25, about 1/12, about1/10, about ⅕, about ¼, about ⅓, ranges between such values, and thelike). A flat radiopaque marker 4210 may have a thickness such that theradiopaque marker 4210 substantially disappears on fluoroscopy when theradiopaque marker 4210 is perpendicular to the imaging plane.

FIG. 42B also shows a length 4230, width 4232, and thickness 4234 of themarker 4210. In some examples, the radiopaque marker 4210 has a length4230 between about 1 mm and about 3 mm (e.g., about 1 mm, about 2 mm,about 2.5 mm, about 3 mm, about 3.5 mm, about 4 mm, about 5 mm, rangesbetween such values, and the like). In some examples, the radiopaquemarker 4210 has a width 4232 between about 0.25 mm and about 3 mm (e.g.,about 0.25 mm, about 0.5 mm, about 1 mm, about 1.5 mm, about 2 mm, about3 mm, ranges between such values, and the like). In some embodiments, aratio of the length 4230 to the width 4232 is between about 1/1 andabout 5/1 (e.g., about 1/1, about 2/1, about 2.5/1, about 3/1, about3.5/1, about 4/1, about 5/1, ranges between such values, and the like).In some examples, the radiopaque marker 4210 has a thickness 4234between about 0.001 mm and about 1 mm (e.g., about 0.001 mm, about 0.002mm, about 0.003 mm, about 0.005 mm, about 0.01 mm, about 0.015 mm, about0.02 mm, about 0.025 mm, about 0.03 mm, about 0.05 mm, about 0.075 mm,about 0.1 mm, about 0.15 mm, about 0.2 mm, about 0.25 mm, about 0.3 mm,about 0.5 mm, about 1 mm, ranges between such values, and the like).

FIG. 42Bi is a schematic side view of another example radiopaque marker4250. The radiopaque marker 4250 may be include the same or similarfeatures as the radiopaque maker 4210, and may be used in the same orsimilar systems and methods. The radiopaque marker 4250 comprises afirst material 4250 a making up a bulk of the radiopaque marker 4250 anda second material 4250 b coupled to the first material 4250 a. In someexamples, a radially outward surface of the radiopaque marker 4250consists of the second material 4250 b. The second material 4250 b maybe more radiopaque than the first material 4250 a (e.g., having adifference enough to discern the second material 4250 b underfluoroscopy). In some examples, the second material 4250 b is radiopaqueand the first material 4250 a is radiolucent. The second material 4250 bcan be coupled to the first material 4250 a via cladding, plating,chemical vapor deposition, atomic layer deposition, screen printing,coating (e.g., dip coating, spray coating), adhesion, sputtering, etc.In certain such examples, the second material 4250 b can be thinner thanthe bulk of the entire radiopaque marker 4250. The first material 4250 amay be polished or otherwise flattened prior to coupling the secondmaterial 4250 b, for example to increase the flatness of the secondmaterial 4250 b coupled thereto. Because the second material 4250 b isthe material used for alignment of the catheter, the second material4250 b (e.g., not the entire radiopaque marker 4250, not the firstmaterial 4250 a) by itself may be considered the radiopaque marker.

In some examples, the second material 4250 b of the radiopaque marker4250 has a thickness 4236 that is less than about 2 μm. In someexamples, the second material 4250 b of the radiopaque marker 4250 has athickness 4236 between about 1 nm and about 10 μm (e.g., about 1 nm,about 2 nm, about 3 nm, about 5 nm, about 10 nm, about 50 nm, about 100nm, about 500 nm, about 1 μm, about 2 μm, about 3 μm, about 5 μm, about10 μm, ranges between such values, and the like). The thickness 4236 ofthe second material 4250 b may depend on the composition of the secondmaterial 4250 b and/or the coupling technique. For example, a metalizednickel layer may be between about 1 μm and about 2 μm. For anotherexample, a layer of gold may be between about 1 nm and about 5 nm orbetween about 1 μm and about 3 μm. Other layers of material are alsopossible. For example, a radiolucent material (e.g., polymer) can becoated over the second material 4250 b to inhibit corrosion of thesecond material 4250 b, to allow use of a second material 4250 b usuallyconsidered non-biocompatible, to follow the contours of the catheter,and/or other reasons. Because the material is radiolucent, the methodsdescribed herein are not affected.

The example dimensions, particularly the thickness, can limit ashadowing effect on angioscopes or x-ray or fluoroscopy machines. Asappreciated from the discussion herein, accurate identification of athin radiopaque marker 4210, 4250 is used for alignment of the catheter4200. A shadow effect may inhibit a user's ability to detect thinness.

The radiopaque marker 4210 is on a side of the catheter 4200, forexample as opposed to being along a diameter or a radius. In someembodiments, the radiopaque marker 4210 is on the same side as theneedle aperture 4208. In some embodiments, the radiopaque marker 4210 ison an opposite side from the needle aperture 4208. Depending on theposition of the radiopaque marker 4210, a goal of the user may be tohave the radiopaque marker proximate to or distant from a targetcatheter.

FIG. 42C is a schematic expanded top view of the distal portion 4204 ofthe launching device 4200 of FIG. 42A. FIG. 42D is a schematic side viewof the distal portion 4204 of the launching device 4200 of FIG. 42A. InFIGS. 42C and 42D, the needle 4216 has been extended out of the needleaperture 4208, for example after alignment of the launching device 4200.In some embodiments, the needle 4216 can be extended by operation of theactuator 4212 relative to the handle 4211. Other mechanisms are alsopossible (e.g., a switch, a slider, a wheel, etc.). A proximal portion4202 having no mechanism or handle 4211 is possible (e.g., a proximalend of the needle 4216 and a proximal end of the catheter 4206 movablerelative to one another by a user holding each proximal end). The needleaperture 4208 is shown proximal to the radiopaque marker 4210, but otheroptions are also possible. For example, the needle aperture 4208 may bedistal to the radiopaque marker 4210. For another example, the needleaperture 4208 may be longitudinally aligned with (e.g., radially outwardof) the radiopaque marker 4210.

In some examples, the needle 4216 may be longitudinally aligned with theradiopaque marker 4210, extending in a plane perpendicular to the thinaxis of the radiopaque marker 4210. Limitation of lateral movement ofthe needle 4216 can reduce positioning error that might otherwise resulteven if the alignment of the radiopaque marker 4210 is correct. Forexample, even if the radiopaque marker 4210 is perfectly aligned, aneedle 4216 that does not extend predictably relative to the radiopaquemarker 4210 can render the alignment meaningless.

FIGS. 42Ci-42Ciii illustrate an example catheter including a profile4260 attached to the needle 4216. The profile 4260 slides in a shapedlumen, which can act as a slot and key system to reduce or minimizelateral and/or rotational movement of the needle 4216. The profile 4260and corresponding lumen can have an asymmetric shape in at least oneradial axis. For example, the C-shape of the profile 4260 interacts witha C-shaped surface of the lumen to inhibit or prevent the needle 4216attached to the profile 4260 from moving laterally. In some examples,the C-shaped surface of the lumen can comprise the outer surface of aguidewire lumen (e.g., for the guidewire 4217 over which the catheter4200 is tracked). Although illustrated in the context of the catheter4200 including the radiopaque marker 4210, a profile 4260 can be used tolaterally stabilize the needle of other catheters described herein(e.g., catheters comprising an ultrasound transducer). Symmetric shapesare also possible. Some implementations can include a sliding lap joint.Some implementations can include an interlocking tube.

When the catheter 4200 is positioned at a viewing angle parallel to amajor axis of the radiopaque marker 4210, for example as shown in FIG.42D, the smallest area of the marker 4210 is visible, which can indicatealignment with a target catheter, for example. Every shift in angleresults in increased visible area, and a goal of the user is to reduceor minimize visible area. Radiopaque markers that are not flat (e.g.,that follow the curvature of the catheter or stent) cannot achieve athin state because the thickness is limited by the curvature and thecircumferential extension of that marker. If the radiopaque marker isnot flat, it may still be used consistent with some of the methodsdescribed herein (e.g., by reducing or minimizing or converselyincreasing or maximizing an amount of visible marker). Upon detection ofalignment, the needle 4216 can extend out of the needle aperture 4208,out of a first vessel (e.g., an artery) in which the catheter 4200resides, through interstitial tissue, and into a second vessel (e.g., avein), for example in which a target catheter resides. Processes asdescribed herein may then be performed (e.g., tracking a guidewirethrough the needle 4216 and using the guidewire for dilation, stentdelivery, a valvulotome, etc. Use of a radiopaque marker 4210, 4250 canreduce or eliminate use of more complicated and/or expensive alignmentsystems such as ultrasound, electric field, and magnets, but stillprovide assurance to the user that the needle 4216 will extend into theneighboring vessel.

In comparison to systems in which two radiopaque components need to bealigned (e.g., radiopaque components on opposite sides of a catheter,one radiopaque component on a side of a catheter and a radiopaquecomponent in a middle of a catheter, one radiopaque component on anextendable member and a radiopaque component elsewhere on a catheter),the radiopaque marker 4210, 4250 can provide less doubt about thealignment. For example, a user may wonder whether one of the radiopaquecomponents is not visible in an imaging plane as opposed to beingaligned or not, whereas the radiopaque marker 4210, 4250 will be visiblewhen not aligned and substantially invisible or at a minimum thicknesswhen aligned, confirmable by small rotations. The use of shapes (e.g.,two radiopaque components forming one shape), bars (e.g., multipleradiopaque components overlapping or separating), etc. can besubjective, whereas the radiopaque marker 4210, 4250 provides asubstantially objective measure of whether any additional rotation makesthe radiopaque marker 4210, 4250 more or less visible. Certain suchshape-based radiopaque component systems may also fail to provideinformation about the direction of the alignment because the shape canbe formed at two or more positions that are, e.g., 180° apart, whereasthe radiopaque marker 4210, 4250 is clearly oriented to a desired side.Even if the shapes separate or become misaligned after rotation, theseparation of the shapes is non-intuitive as to direction. Certain suchshape-based systems simply confirm that rotation has occurred withoutregard to alignment. A radiopaque dot on a side of a catheter, lackinglength and width dimensions, may provide similar limited visibility inall rotational orientations, whereas the radiopaque marker 4210, 4250shows prominently when not aligned. Subjective alignment of shapes orassessment of widths (as opposed to objective assessment of minimalthickness) can cause a few degrees of misalignment which can cause theneedle to miss the second vessel when crossing from a first vessel to asecond vessel. A radiopaque hoop, for example around a circumference ofa catheter, can provide information about the position of the imagingsystem to the catheter (e.g., whether parallel or perpendicular to thecatheter), but does not provide rotational information about thecatheter, such that the change from a circular pattern to a linearpattern is not useful for rotationally aligning the catheter. Theelegant nature of the radiopaque marker 4210, 4250 can reducemanufacturing costs, for example because a complex shape and positionmay be avoided.

FIGS. 43A-43N schematically illustrate an example method of using alaunching device including the distal portion 4204 of the launchingdevice 4200 of FIG. 42A. In FIGS. 43A-43G, the radiopaque marker 4210 isshown in an enlarged view. In some embodiments, the method may beginafter performing the method of FIGS. 39A-39E (e.g., expanding anexpandable structure or snare 1504 of a target catheter), and certainfeatures may be shared between the methods.

In FIG. 43A, the distal portion 4204 has been longitudinally advanced ina first vessel to a position longitudinally proximate to a snare 1504.The snare 1504 in this example is radiopaque and can be used as a targetcatheter. Other target catheters are also possible, for example havingradiopaque markers on a catheter (e.g., a first radiopaque markerlongitudinally spaced from a second radiopaque marker, the markerscomprising marker bands in some embodiments), including a balloon filledwith radiopaque material, etc. A user can see the radiopaque marker 4210and a radiopaque feature of a target catheter under fluoroscopy.

In FIG. 43B, the distal portion 4204 is rotated, as indicated by thearrow 4302. During rotation, the radiopaque marker 4210 becomes thinner.In FIG. 43C, the distal portion 4204 is further rotated, as indicated bythe arrow 4304. During rotation, the radiopaque marker 4210 becomesthinner. At this point, a user may think that the thin radiopaque marker4210 indicates alignment, but the radiopaque marker 4210 is on a side ofthe launching catheter that is opposite the snare 1504. For thisarrangement in which the radiopaque marker 4210 is on the same side asthe needle aperture 4208, the radiopaque marker 4210 should be proximateto the snare 1504. The radiopaque marker 4210 being relatively proximateor distant to the snare 1504 is viewable during rotation. In someembodiments, a guidewire having radiopaque properties can help determinethe side of the radiopaque marker 4210. Because the radiopaque marker4210 is thin but on the wrong side in FIG. 43C, the user continuesalignment.

In FIG. 43D, the distal portion 4204 is further rotated, as indicated bythe arrow 4306. During rotation, the radiopaque marker 4210 becomesthicker. In FIG. 43E, the distal portion 4204 is further rotated, asindicated by the arrow 4308. During rotation, the radiopaque marker 4210becomes thinner. In FIG. 43F, the distal portion 4204 is furtherrotated, as indicated by the arrow 4310. During rotation, the radiopaquemarker 4210 becomes thinner. The radiopaque marker 4210 is now proximateto the snare 1504 and thin, indicating alignment. In some embodiments,the alignment may stop at this point.

In FIG. 43G, the distal portion 4204 continues to be rotated or isover-rotated in the direction indicated by the arrow 4312. Duringrotation, the radiopaque marker 4210 becomes thicker, indicating thatthe further rotation is making alignment worse. In FIG. 43H, the distalportion 4204 is rotated in the opposite direction, as indicated by thearrow 4314. During rotation, the radiopaque marker 4210 becomes thinner.The radiopaque marker 4210 is now again proximate to the snare 1504 andthin, indicating alignment. The further rotations of FIGS. 43G and 43Hcan help to ensure a user that the alignment is correct (e.g.,optimized). Rotation of the distal portion 4204 and viewing of theradiopaque marker 4210 can be similar to focusing a camera, where a usercan do a coarse adjustment and a fine adjustment. For example, thecoarse adjustment can be to determine whether or not the radiopaquemarker 4210 is on the side proximate to the snare 1504, and the fineadjustment can be to reduce the area of the radiopaque marker 4210. Thealignment may also be described as a pendulum where the user rotates thedistal portion 4204 back and forth to find a low or minimum thickness ofthe radiopaque marker 4210. Thus may include over-rotation, over-swing,over-shoot, etc. to confirm alignment.

FIG. 43Hi schematically shows alignment of a radiopaque marker through arotational alignment process. A catheter comprising the radiopaquemarker is in a first vessel proximate or adjacent to a target vessel.The catheter is tracked over a guidewire 4217 comprising radiopaquematerial. When the radiopaque marker overlaps the guidewire 4217, eitherthe front or back (or first side and opposite second side) of theradiopaque marker is visible. In this example, the radiopaque marker ison a same side of the catheter as the needle aperture. When theguidewire 4217 is between the radiopaque marker and the target, thecatheter is rotationally misaligned by about 90° to about 270°. Forexample, even if the radiopaque marker is thin, as shown by theright-most illustration in FIG. 43Hi, the catheter would be 180°misaligned. When the radiopaque marker is between the guidewire 4217 andthe target, the catheter is rotationally on the correct side of thecatheter. When on the correct side of the catheter and thin, as shown bythe left-most illustration in FIG. 43Hi, the catheter is aligned. If theradiopaque marker is thin enough, the radiopaque marker may be a thinline or even disappear from the fluoroscopy. If the radiopaque marker ison an opposite side of the catheter as the needle aperture, the processwould be the opposite with respect to the guidewire 4217. The process isalso possible without a guidewire 4217 or if the guidewire 4217 is notradiopaque, as the user can visualize the radiopaque marker being nearor far from the target during rotation. Visualization through a range ofrotational positions including the radiopaque marker being thin on bothsides can inhibit, minimize, or prevent 180° misalignment.

Once the launching catheter is aligned, the needle 4216 can be extended,as shown in FIG. 431 . Extending the needle may include exiting a firstvessel in which the distal portion 4204 resides, traversing interstitialtissue, and entering a second vessel in which the snare 1504 resides. Inembodiments, the needle 4216 crosses into the snare 1504. In FIG. 43J, aguidewire 4218 is extended through the needle 4216. The guidewire 4218thereby extends through the first vessel, through the interstitialtissue, and into the second vessel.

In FIG. 43K, the snare 1504 is moved distally, as indicated by the arrow4316. The guidewire 4218 also moves distally, indicating that theguidewire 4218 is captured or entangled by the snare 1504. If the snare1504 is moved distally before retraction of the needle 4216, distalmovement of the needle 4216 can confirm engagement with the snare 1504and/or being in the interior of the target vessel. Verification usingthe needle 4216 can be before or after advancing the guidewire 4218. Insome examples, the needle 4216 can be verified, then the guidewire 4218can be advanced, and the guidewire 4218 can be verified. In FIG. 43L,the sheath 1502 is distally advanced, as indicated by the arrow 4318,capturing the snare 1504 and the guidewire 4218 entangled with the snare1504. In FIG. 43M, the sheath 1502 is further distally advanced, asindicated by the arrow 4320, further capturing the snare 1504. In someembodiments, the snare 1504 may not be fully retrievable into the sheath1502, for example due to the entanglement with the guidewire 4218. Thesnare 1504 may nevertheless be radially compressed enough to movethrough the second vessel.

In FIG. 43N, the snare 1504 is proximally retracted, as indicated by thearrow 4322. Because the guidewire 4218 is entangled with the snare 1504,the guidewire 4218 is also proximally retracted in the second vessel,or, relative to the first vessel, distally advanced. As describedherein, for example, a snare technique can help to navigate theguidewire 4218 through the second vessel, for example past valves andother difficult vasculature. Catheters comprising a valvulotome, astent-graft, and the like may be tracked over the guidewire 4218 andthrough the second vessel, for example as described herein.

Software may be implemented to aid in detection of the radiopaque marker4210. The software may, for example, establish a “crossing plane”between first and second catheters and/or vessels (e.g., between a firstcatheter and a second catheter, between a first vessel and a secondvessel, between a first catheter in a first vessel and a second vessel).To be “in the crossing plane” generally means, without limitation, thatwhen the user advances a needle from the first vessel to the secondvessel, the needle will enter the second vessel. This crossingpreferably allows procedures to be performed such that fluid flowsbetween the vessels. The crossing plane may be obtained via fluoroscopyor other imaging systems, for example by rotating the imaging head(e.g., “C-arm”) until the two vessels of interest (or a catheter in oneor both of the vessels) are substantially at a maximum distance fromeach other. When the first vessel and second vessel are parallel, and attheir maximum distance, one can say that they are in the “crossingplane” now displayed. This can be a challenging task, as measurementbetween vessels/catheters is typically rudimentary or done “by eye.” Asoftware solution can make the process more exact and with feweruser-driven errors (e.g., providing better precision, more reliability),and possibly more quickly.

The software may run in parallel with other software (e.g., imagingsoftware). FIGS. 430i-430 vi illustrate an example implementation ofalignment using software. In FIG. 430 i , a first catheter 4200 isadvanced in a first vessel 4330 and a second catheter 1500 is advancedin a second vessel 4332 proximate to an intended crossing point (e.g.,proximate to and/or upstream of an occlusion in the first vessel 4330).The first vessel 4330 may be an artery. The second vessel 4332 may be avein. The “C-arm” or other holder of an imaging system may be positionedsuch that it does not immediately provide an appropriate view of thevessels 4330, 4332 and/or catheters 4200, 1500. In FIG. 430 ii, thesoftware measures a distance 4338 between a centerline 4334 of the firstcatheter 4200 and a centerline 4336 of the second catheter 1500. As theC-arm is rotated, the distance 4338 changes because the imaging planechanges. The system may control the C-arm and/or may be responsive to auser moving the C-arm. When the distance 4338 is at a maximum and/or isgreater than a certain amount, the software identifies a crossing plane.The detection may be magnification dependent. When the crossing planehas been identified, the system can send a signal to a user (e.g.,audible such as a beep, visual such as changing the color, dashing,thickness, etc. of the centerlines 4334, 4336, tactile such as vibrationof a handle, sending a signal to a remote computing device, combinationsthereof, and the like). The system may be fully or partially automated(e.g., moving on to the next step without user interaction or only uponuser interaction). Combinations of line drawing and/or measurementmethods/software may be used. In FIG. 430 iii, the image of the crossingplane optionally may be oriented as desired (e.g., such that the vessels4330, 4332 are parallel to the lateral edges of the viewing area). Insome implementations, the vessels 4330, 4332 may be filled with contrastin the viewing area, and a distance between their centerlines or an areabetween the contrast-filled vessels 4330, 4332 could be maximized and/orgreater than a certain value to identify the crossing plane. Suchtechniques may be particularly suitable for non-parallel vessels 4330,4332. Depending on the imaging system, contrast may be omitted, forexample if the vessels 4330, 4332 can be identified without contrast.Combinations of catheter identification and/or vessel identification maybe used.

The first catheter 4200 may be rotated as indicated by the arrow 4340until the radiopaque marker 4210 has a minimum thickness or a thicknesslower than a certain value. The software may use edge detection or othermethods to identify the thickness of the radiopaque marker 4210 duringrotation. FIG. 43Ov shows edge lines 4342, 4344 used to measure athickness of the radiopaque marker 4210 as a distance between the edgelines. The software may use the same or similar routines to identifyedges of the radiopaque marker 4210 as to identify the centerlines 4334,4336 in FIG. 430 ii. The software may use the same or similar routinesto measure the distance between the edge lines 4342, 4344 as thedistance 4338 between the centerlines 4334, 4336 in FIG. 430 ii. In someimplementations, a pixel count may be used. As described above, thesoftware also accounts for the position of the second vessel and thuscan establish whether the thin radiopaque marker is facing the secondvessel (or vice versa). Once the software has established that thethickness of the radiopaque marker 4210 indicates that the firstcatheter 4200 is properly aligned, and that the first catheter 4200 isfacing the second vessel 4332, a needle 4216 can extend from the firstcatheter 4200, out of the first vessel 4330, and into the second vessel4332. When rotational alignment has been identified (e.g., that thecatheter is facing the correct direction and that the crossing needlewill be “in the crossing plane”), the system can send a signal to a user(e.g., audible such as a beep, visual such as changing the color,dashing, thickness, etc. of the edge lines 4342, 4344, tactile such asvibration of a handle, sending a signal to a remote computing device,combinations thereof, and the like). The needle extension can beinitiated by a user after receiving the signal. The needle extension canbe automatic upon indicating alignment. The system may be fully orpartially automated (e.g., moving on to the next step without userinteraction or only upon user interaction). The second catheter 1500 maybe moved longitudinally to move the needle 4216 to confirm that theneedle has punctured the expandable member of the second catheter 1500,for example as described herein.

Navigation of a guidewire for retrograde venous access (e.g., againstthe direction of normal blood flow) can be difficult or even impossible,for example due to venous valves intended to prevent venous reflux andthe many tributaries and parallel venous structures. Retrogradeguidewire navigation of veins can result in diversion into branches,obstruction as a result of valves, either or both of which can causespasm and/or perforation. Advancing a guidewire distally past a tibialvenous sheath insertion point, for example, can be time-consuming,sometimes taking several hours without a pedal/tibial venogram toprovide a road map and/or because the peripheral vasculature,particularly distal to the heart, varies between people. Keeping theaccess sheath and guidewire in the tibial vein can help tension or tentthe vein to allow the exchange catheter and retrograde guidewire to passdistal to the tibial access sheath. Failure to stay in the vein, whichcan lead to perforations, can cause vein spasms such that a proceduremay need to be aborted because the user is unable to access the foot.

Advancing a guidewire around a pedal arch without a venogram or road mapcan lead to perforate veins and/or induce venous spasm. Perforating avein can cause a compartment around the vein which essentially flattensthe vein, hindering navigation or making navigation impossible. After aperforation, it is possible to wait 15-20 minutes to see if theperforation has resolved, try selecting an alternative venous pathway,or aborting the procedure. The user may elect to try again in a fewdays, for example when the perforation should be resolved. Whenadvancing a guidewire into the foot, a user can flex the foot, use areverse Trendelenburg posture (head elevated above feet), and/or apply atourniquet above the ankle to increase venous pressure, therebyexpanding the diameter of the vein and making navigation through valvesin the vein easier, but these may not fully address perforation risk.

Antegrade pedal access offers both the opportunity for pedal venousimaging and the passage of a guidewire in a chosen vessel without thecomplications of valvular obstruction and diversion into branch vessels.A technique to perform consistent antegrade pedal venous access caninclude, for example, the use of ultrasound, techniques for venousdilatation, and/or fluoroscopic imaging.

When retrograde access to the pedal venous vasculature is desired, aninitial antegrade access from the target pedal venous structure canallow the passage of a guidewire without venous valve obstruction, forexample because. the guidewire is following the natural course of venousflow. An appropriately-shaped guidewire designed to align to thecenterline that is introduced in this fashion has less chance ofdiversion into the multiple side branches, perforators, and parallelvenous structures. Once a guidewire is introduced from the pedal targetvein in this antegrade fashion, other catheters and devices can beintroduced in a retrograde fashion with limited or without obstructionfrom valves that are effaced by the guidewire and/or risk of diversioninto branch vessels.

Accessing a posterior tibial vein above the ankle and up to a crossingpoint, then with a crossing guidewire working in a retrograde fashionnavigating past the tibial sheath and trying to get to the venous archin the foot can be difficult, or given certain anatomy, may not even bepossible. Understanding the foot anatomy can help a user access desiredveins in the foot, for example because a user pass a guidewire into theconnecting tibial vein and up to the crossing point, eliminating anyconfusion on the potential pathway.

FIG. 44A illustrates vascular anatomy of an example foot 4400. The foot4400 includes a medial marginal vein 4402. The medial marginal vein 4402continues towards the heart as the great saphenous vein 4401. FIGS. 44Eand 44F also show the great saphenous vein 4401. The foot 4400 includesperforating or branch veins feeding the medial marginal vein 4402,including a submalleoral vein 4403, a scaphoid vein 4404, a cuneal vein4405, and perforating or branch veins feeding these veins. The foot 4400includes a first intermetatarsal space perforator vein 4406. Thesubmalleoral vein 4403, scaphoid vein 4404, cuneal vein 4405, and firstintermetatarsal space perforator vein 4406 are connected to the medialplantar veins 4407. The first intermetatarsal space perforator vein 4406provides a consistent venous connection from the top or dorsal side ofthe foot 4400 to the bottom or plantar side of the foot 4400. Thelateral functional unit of the foot 4400 includes lateral plantar veins4408 and a calcaneal perforator vein 4409. In the rear of the foot 4400,the lateral plantar veins 4408 and the calcaneal perforator vein 4409form two confluences that originate plexiform posterior tibial veins4010.

FIG. 44B further illustrates vascular anatomy of the example foot 4400.As also shown in FIG. 44A, the foot 4400 includes a medial plantar vein4407 and a lateral plantar vein 4408. The bottom of the foot 4400includes a perforator of the first metatarsal interspace 4406. The foot4400 includes toe veins including the first digital vein 4414 and thefourth digital vein 4416. The foot 4400 includes a cuboidal perforator4418. The foot 4400 includes a malleolar perforator 4420. The foot 4400includes a navicular perforator 4422.

FIG. 44C shows a first dorsal metatarsal artery 4424, and extender 4426,a digital artery to great and second toes 4428, a deep peroneal nerve4430, and a dorsal vein 4432. FIG. 44D shows plantar metatarsal veins4434, medial plantar vein 4407, posterior tibial vein 4438, lateralplantar vein 4408, and deep plantar venous arch 4442. FIG. 44D alsoshows the first metatarsal perforator 4406, which connects plantar todorsal veins. FIG. 44E shows the posterior tibial vein 4438, the lateralplantar vein 4408, the medial plantar vein 4407, and the medial marginalvein 4402.

FIG. 44G shows the great saphenous vein 4401, the medial marginal vein4402, and the deep peroneal nerve 4430. In addition, FIG. 44G shows thesuperficial peroneal nerve 4440, the saphenous nerve 4442, the smallsaphenous vein 4444, medial perforating veins 4446, lateral perforatingveins 4448, the sural nerve 4450, the lateral marginal vein 4452, andthe dorsal venous arch 4454.

FIG. 44H shows the medial plantar vein 4407, the lateral plantar vein4408, and the small saphenous vein 4444. In addition, FIG. 44H showsperforators of the femoral canal 4456, an anastomosis to the deepfemoral vein 4458, the femoral vein 4460, the popliteal vein 4462, themedial and lateral gastrocnemius veins 4464, a soleal vein 4466, theanterior tibial vein 4468, paratibial perforators 4470, soleal veins4472, a soleal vein 4474, peroneal veins 4476, posterior tibial veins4478, lateral leg perforators 4480, the upper posterior tibialperforator 4482, the middle posterior tibial perforator 4484, the lowerposterior tibial perforator 4486, and the medial ankle perforator 4488.

FIG. 441 is an inferior view of an anatomical dissection of lower footveins. FIG. 441 shows medial plantar veins 4407, lateral plantar veins4408 (double), and the navicular perforator 4422. In addition, FIG. 441shows the calcaneal crossroad 4488 of the plantar veins, a plexus-shapednetwork 4490 of the sole, the perforator 4492 of the intermetatarsalspace, and a perforator 4494 of the fifth metatarsal bone.

FIG. 44J is a medial view of an anatomical dissection of lower footveins. FIG. 44J shows medial marginal vein 4402, the great saphenousvein 4401, the anterior tibial vein 4468, and the perforator vein 4492of the first intermetatarsal space. In addition, FIG. 44J shows a dorsalperforator vein 4496 that is communicating with the anterior tibial vein4468, the submalleolar foot perforator vein 4498, the navicularperforator vein 4423, the dorsal arcade 4495 of the foot, a dorsalperforator vein 4497, and the dorsal vein 4499 the of Hallux.

Certain techniques of deep vein arterialization of the foot can targetarterial inflow at the level of the pedal veins and retrograde flow intothe venous pedal arch, which is the continuation of the lateral ormedial plantar vein(s) through the first intermetatarsal spaceperforator and into the anterior tibial venous vein(s).

FIG. 45 shows example components of a kit 4500 that may be used forpedal access. The kit 4500 includes a tourniquet 4502, an ultrasoundprobe 4504, and a puncture set 4506. The tourniquet 4502 may comprise apneumatic tourniquet 4502 a. The tourniquet 4502 may comprise an Esmarchtourniquet 4502 b. The kit 4500 may comprise a series of tourniquets4502 having various sizes (e.g., as shown in FIG. 45 ) and/or varioustypes of tourniquets 4502 (e.g., as shown in FIG. 45 ). The ultrasoundprobe 4504 may comprise ultrasound appropriate for high definitionvenous imaging of target pedal vessels. The kit 4500 may comprise aliquid or gel configured for use with the ultrasound probe 4504. Thepuncture set 4506 may comprise an echogenic needle 4508 and a guidewire4510. The needle 4508 would be compatible with the diameter of theguidewire 4510, and may be selected based the depth and anatomiclimitations of pedal venous structures. The needle 4508 may be fittedwith a Tuohy-Borst adaptor to prevent backflow of blood. The guidewire4510 may be, for example, 0.018 inches. The puncture set 4506 maycomprise a dilator (e.g., a 2.9 Fr inner dilator fitted within a sidearm for injection). The kit 4500 may comprise multiples of the describedcomponents, additional components, and/or may lack one or more of thedescribed components. Some or all of the components of the kit may besterile. For example, the ultrasound probe 4504 can be covered with asterile bag, whereas the puncture set 4506 used must be sterile.

An example procedure, for example using the kit 4500, comprises using anultrasound probe 4504 on the surface of the foot to guide a puncturerwith a needle 4508. A guidewire 4510 is then inserted through the needle4508. In some embodiments, a dilator 4512, optionally including a sidearm for injections, may be optionally tracked over the guidewire 4510.The guidewire 4510 is then removed. Contrast is injected into thedilator 4512 (e.g., through the optional side arm). The volume ofcontrast may be, for example, about 5 mL to about 50 mL (e.g., about 5mL, about 10 mL, about 15 mL, about 20 mL, about 25 mL, about 30 mL,about 35 mL, about 40 mL, about 45 mL, about 50 mL, ranges between suchvalues, etc.). The contrast may be a solution, for example about 50%contrast and about 50% saline. The contrast extends to the veins in thetop of the foot, the bottom of the foot, and up towards the ankle,providing a roadmap of the venous vasculature in the foot. The same or adifferent guidewire 4510 may then be inserted into the dilator 4512 andnavigated into the venous anatomy of the user's choice based on all ofthe known veins.

In some examples, the subject can be set in a reverse Trendelenburgposition, with the head being elevated above the feet, for examplebetween about 30 degrees and to about 45 degrees. Fluoroscopy (e.g.,Digital Subtraction Imaging (DSI) selecting a large (e.g., maximum)frame size that includes all images/pathways of the veins in the foot,for example, can be used to visualize aspects of the procedure.

A first tourniquet can be positioned above the knee and a secondtourniquet can be positioned above the ankle on the leg of interest. Thefirst tourniquet can at least partially contribute to expanding theveins below the knee. The second tourniquet may at least partiallycontribute to expanding the veins below the ankle. The first tourniquetcan be the same type and/or size as the second tourniquet (e.g., bothbeing pneumatic tourniquets; both being Esmarch tourniquets; etc.). Thefirst tourniquet can be different than the second tourniquet in sizeand/or type (e.g., one being a pneumatic tourniquet and the other beingan Esmarch tourniquet; both being pneumatic tourniquets having differentsizes; etc.). The second tourniquet can block contrast from enteringsuperficial veins, forcing the contrast into the deep veins.

In some embodiments, a metatarsal vein 4434, dorsal or plantar, can beused for injection of contrast. Palpating or tapping the vein ofinterest with fingers can improve success rate of the vein dilating.When the metatarsal vein 4434 is successfully cannulated, the secondtourniquet around that ankle should be tight and/or should remain tight.The subject may be flattened on the table (e.g., if originally in areverse Trendelenburg position). Contrast may be injected into thevenous vasculature from the metatarsal vein 4610 (e.g., for an ascendingvenogram procedure). Contrast may be injected into the venousvasculature from the great saphenous vein towards the foot (e.g., for adescending venogram procedure). One or both of the tourniquets can blockcontrast from entering the superficial veins, forcing the contrast intothe deep veins. Anteroposterior (AP) and lateral views can be takenunder fluoroscopy.

Non-ionic contrast can be used. The contrast may be warmed for ease ofuse, but is preferably not warmed greater than body temperature. Thecontrast may comprise a 50/50 mixture or dilution. For example, thecontrast may comprise, about 15 mL of contrast diluted with 15 mL ofsaline. The contrast may comprise a total volume injection between about5 mL and about 50 mL (e.g., about 5 mL, about 10 mL, about 15 mL, about20 mL, about 25 mL, about 30 mL, about 35 mL, about 40 mL, about 45 mL,about 50 mL, ranges between such values, etc.). All or substantially allof the veins of the foot that may be potentially used for pedal accessmay be mapped by this quantity of contrast. More or less contrast can beused based on the subject (e.g., more for larger subjects, less forsmaller subjects and/or subjects with partial feet). The secondtourniquet around the ankle may be removed after mapping the veins ofthe foot, keeping the first tourniquet above the knee on and in place.

The injection site may be continuously monitored for possibleextravasation of the contrast into soft tissue of the subject's foot. Ifcontrast extravasation is detected, the user may apply slight pressureto the access site to slow down/stop the extravasation, and continue tomonitor.

If an occlusion is in an anterior tibial artery, pedal access may targetthe anterior tibial vein. A tourniquet is first placed above the ankle(e.g., to expand the veins). Guided by ultrasound, ascending venousaccess (towards the leg) may be obtained with a needle in the dorsalfirst metatarsal vein 4610 (aligned with the medial vein). A 21 gaugeneedle, for example, can accommodate a 0.018″ guidewire. An atraumaticguidewire (e.g., having a J-shaped tip) can be advanced into the firstmetatarsal vein 4610. Once the guidewire is in the first metatarsal vein4610, the needle can be removed, leaving the cannula or inserting aninner dilator. The first metatarsal vein 4610 may then be flushedthrough a side arm with heparinized saline. If the cannula is notproperly positioned in the first metatarsal vein, the skin will blisterwith saline. Another method for checking positioning is to inject asmall amount of a contrast medium (e.g., if the contrast flows throughthe vein, if the contrast pools around the vein). Another method forchecking positioning is to aspirate to see if blood comes out.Preferably, at least one check is performed to make sure the cannula isproperly positioned in the vein prior to injection of a large amount ofcontrast medium. A dorsal and plantar venogram can be performed with aninjection of contrast medium (e.g., about 5 mL to about 50 mL). A targettibial vein is selected using the venogram, and the guidewire isadvanced to the target tibial vein. The tourniquet can be removed oncethe guidewire is in the target tibial vein. The guidewire can then beused to track devices (e.g., a target catheter for forming a fistula)through the target tibial vein.

If an occlusion is in a posterior tibial artery, which is more commonthan an anterior tibial artery, pedal access may target a lateralplantar vein. A tourniquet is first placed above the ankle (e.g., toexpand the veins). Guided by ultrasound, ascending venous access(towards the leg) may be obtained with a needle in the dorsal medialmarginal vein 4402 (towards the toes). A 21 gauge needle, for example,can accommodate a 0.018″ guidewire. An atraumatic first guidewire (e.g.,having a J-shaped tip) can be advanced into the first metatarsal vein.Once the first guidewire is in the first metatarsal vein, the needle canbe removed, leaving the cannula or inserting an inner dilator. Thedorsal medial marginal vein 4402 may then be flushed through a side armwith heparinized saline. If the cannula is not properly positioned inthe dorsal medial marginal vein 4402, the skin will blister with saline.Another method for checking positioning is to inject a small amount of acontrast medium and see what happens (e.g., if the contrast flowsthrough the vein, if the contrast pools around the vein). Another methodfor checking positioning is to aspirate fluid to see if blood comes out.Preferably, at least one check is performed to make sure the cannula isproperly positioned in the vein prior to injection of a large amount ofcontrast medium. A dorsal and plantar venogram can be performed with aninjection of contrast medium (e.g., about 5 mL to about 50 mL).

Since the occlusion is in a posterior tibular artery, methods describedherein can divert oxygenated blood from the posterior tibial artery intothe posterior tibial vein. The larger of the two lateral plantar veinsis selected using the venogram, and the first guidewire is advanced to acrossing point or at least above the ankle. Again using ultrasoundguidance on the skin, the plantar veins may be surveyed from the bottomof the foot to view the position of the first guidewire.

The second access should be made as distal as possible in the plantararch with a needle in the lateral plantar vein with the first guidewiretherein. A 21 gauge needle, for example, can accommodate a 0.018″guidewire. An atraumatic second guidewire (e.g., having a J-shaped tip)can be advanced into the lateral plantar vein and then into theposterior tibial vein and up to the crossing point. Once the secondaccess has been made, the first guidewire could be removed. In someexamples, once the second access point has been selected, the firstguidewire could be removed. The ankle tourniquet can be removed once thesecond guidewire is in the target posterior tibial vein. The secondguidewire can then be used to track devices (e.g., a target catheter forforming a fistula) through the target posterior tibial vein. If a usertried to advance the first guidewire to the posterior tibial vein fromthe top of the foot, the first guidewire would be at a weak position andcould tear tissue. The second guidewire is on the bottom of the footwhere the veins are larger, and provides more robust access.

Example procedures for performing an ascending venogram, dorsal orplantar, procedure, are described in FIGS. 46A-46H with reference to theanatomy described in FIGS. 44A-44F and the kit 4500 of FIG. 45 .

In FIG. 46A, a tourniquet 4602 is placed above the ankle to increasevenous pressure in the foot. In FIG. 46B, the great saphenous vein 4401is located. In some examples, the medial malleolus 4604, which is aprominence on the inner side of the ankle formed by the lower end of thetibia, can be used to help locate the great saphenous vein 4401. In FIG.46C, the great saphenous vein 4401 is traced toward the toes. The greatsaphenous vein 4401 leads to the medial marginal vein 4402. Theintersection between the great saphenous vein 4401 and the medialmarginal vein 4402 is the location of the first access site 4606, markedby a red X in FIG. 46D. Tapping the medial marginal vein 4402, forexample with a user's fingers, can increase vasodilation, asschematically illustrated in FIG. 46E. FIG. 46E still shows the firstaccess site 4606.

In FIG. 46F, a first needle 4608 is used at the access site 4606 toaccess the medial marginal vein 4402 towards the toes. In some examples,the first needle 4608 may comprise a 21 gauge needle. A quantity ofcontrast fluid is injected through the first needle 4608. In someexamples, the contrast comprises contrast fluid diluted with saline. Insome examples, the quantity comprises between about 5 mL and about 50 mL(e.g., about 5 mL, about 10 mL, about 15 mL, about 20 mL, about 25 mL,about 30 mL, about 35 mL, about 40 mL, about 45 mL, about 50 mL, rangesbetween such values, etc.). The contrast provides a roadmap venogram foridentifying a second assess site.

In FIG. 46G, the first metatarsal perforator 4406 connects plantar veinson the bottom of the foot to dorsal veins on the top of the foot. InFIG. 46H, a second needle 4609 is used at a second access site 4610proximate to the first metatarsal perforator 4406 to access a lateralplantar vein 4408 towards the fifth toe. In some examples, the secondneedle 4609 may comprise a 21 gauge needle. In FIG. 461 , a guidewire4612 is used to access the lateral plantar vein 4408, for example withthe tip of the guidewire 4612 prolapsed. In some examples, the guidewire4612 may comprise an 18 gauge guidewire. An 18 gauge guidewire 4612 canfit through the lumen of a 21 gauge needle. In FIG. 46J, the guidewire4612 is advanced through the lateral plantar vein 4408 into theposterior tibial vein 4438.

The tourniquet 4602 can be removed. In some examples, the tourniquet4602 or a different tourniquet can be placed above the knee. Underultrasound guidance, the tibial vein 4614 with the guidewire 4612therein can be selected for placement of a tibial access sheath, asshown in FIG. 46K. In some examples, the tibial access sheath comprisesa 5 Fr sheath. The guidewire 4612 can be used for a vein targetingprocedure, for example as described herein. The guidewire 4612 can beused for over-the-wire procedures such as fistula formation (e.g., atarget catheter, a launching catheter), prosthesis placement, valvedisabling, vessel lining, etc., as described herein, and the like. Thepedal access procedures described herein can advantageously provideunique access point that can provide a greater amount of access to footvessels, which can provide more flexibility in procedures and/or moreaccess to affect vessels.

In some examples, a method comprises inserting a reentry catheter (e.g.,Outback, available from Cordis) into a pedal vein to access a tibialvein, inserting a snaring device in an arterial vasculature, trackingthe snaring device to a tibial artery adjacent to the tibial vein,advancing a needle of the reentry catheter from the tibial vein towardsthe snare in the tibial artery, advancing a wire through the needle,snaring the wire, and retracting the snare out of the arterialvasculature. The wire can be used, for example, to create a fistula,position a prosthesis or multiple prostheses, disable valves, etc., forexample as described herein.

The present application discusses several examples in which a guidewireadvanced through a fistula from a first vessel into a second vessel iscaptured by a snare. In some examples, a valvulotome (e.g., reversevalvulotome or two-way valvulotome) is advanced over the guidewire afterthe guidewire has been pulled through the vessel by the snare. In someexamples, a valvulotome or cutting device may be integrated or otherwiseincorporate with the snare in a cutting snare system. A cutting snaresystem can provide advantages such as reducing an overall number ofsteps in a procedure, reducing a number of device exchanges, reducingprocedure time, improving effectiveness of a valvulotome, reducingprocedure components, improving procedure cost of goods, and/or otheradvantages.

FIG. 47A is a perspective view of a portion of an example cutting snaresystem 4700. The cutting snare system 4700 comprises a snaring mesh 4702and cutting blades 4706. The snaring mesh 4702 may be cut from ahypotube to form cells capable of or configured to receive a guidewire(e.g., having an area greater than a diameter of a guidewire to besnared) and struts capable of or configured to capture a guidewire. Thecutting snare system 4700 may be tracked over a guidewire (e.g., with anouter sheath) or tracked through a lumen of a catheter (e.g., thecatheter acting as the outer sheath).

The illustrated cutting snare system 4700 includes four cutting blades4706 circumferentially spaced by about 90°. Other quantities of blades4706 are also possible. For example, the cutting snare system 4700 maycomprise one to eight cutting blades 4706 (e.g., 1 blade, 2 blades, 3blades, 4 blades, 5 blades, 6 blades, 7 blades, 8 blades, and rangesbetween such values). More than 8 cutting blades 4706 are also possible.In some examples (e.g., as shown in FIG. 47A), the cutting blades 4706may be longitudinally aligned. In some examples, the cutting blades 4706may be longitudinally offset. In some examples (e.g., as shown in FIG.47A), the cutting blades 4706 may be evenly circumferentially spaced(e.g., two blades may be circumferentially spaced by about 180°, threeblades may be circumferentially spaced by about 120°, four blades may becircumferentially spaced by about 90°, five blades may becircumferentially spaced by about 72°, six blades may becircumferentially spaced by about 60°, seven blades may becircumferentially spaced by about 51°, eight blades may becircumferentially spaced by about 45°, etc.). In some examples, thecutting blades 4706 may be circumferentially unevenly distributed.

The snaring mesh 4702 has a first outer diameter and the cutting blades4706 have a second outer diameter. In some examples, the second outerdiameter is less than the first outer diameter, which can allow thesnaring mesh 4702 to appose sidewalls of the second vessel without thecutting blades 4706 cutting the sidewalls of the second vessel. Wherecutting of valves in the second vessel is desired, the valves extendinto the second vessel and are able to be cut by the cutting blades4706.

The cutting snare system 4700 has an expanded state and a compressedstate. The cutting snare system 4700 may comprise shape memory (e.g.,superelastic) material (e.g., nitinol, chromium cobalt, etc.). Thecutting snare system 4700 may comprise stainless steel. The cuttingsnare system 4700 may comprise polymer. The cutting snare system 4700may be configured to expand from the compressed state towards theexpanded state in the absence of radially inward forces (e.g., from asheath). In some implementations, the cutting snare system 4700 may beexpanded upon application of a longitudinal force to one part of thecutting snare system 4700 (e.g., a proximal end or a distal end)relative to another part of the cutting snare system 4700 (e.g., adistal end or a proximal end).

The snaring mesh 4702 can capture a guidewire, for example as describedwith respect to other procedures herein. Capturing the guidewire mayinclude radially compressing the snaring mesh 4702 towards thecompressed state (e.g., by capturing a proximal portion of the cuttingsnare system 4700 in a sheath, reversing a longitudinal expansion force,etc.). The cutting snare system 4700 is then pulled proximally, asindicated by the arrow 4707. As the cutting snare system 4700 is pulledthrough the second vessel, the cutting blades 4706 can cut valves of thesecond vessel using the same movement or physical act. In some examples,the cutting snare system 4700 can be maneuvered across a valve multipletimes to increase cutting.

FIGS. 47Bi and 47Bii are side views of another example cutting snaresystem 4710. The cutting snare system 4710 comprises a snare structure4712 and a valvulotome structure 4714 in series. The snare structure4712 may be proximal to the valvulotome structure 4714 (e.g., asillustrated in FIG. 47Bi). The snare structure 4712 may be distal to thevalvulotome structure 4714 (e.g., as illustrated in FIG. 47Bi). Thesnare structure 4712 may be monolithic or integrally formed with thevalvulotome structure 4714 (e.g., as illustrated in FIG. 47Bi). Forexample, the snare structure 4712 and the valvulotome structure 4714 maybe cut from a same hypotube. A monolithic snare structure 4712 andvalvulotome structure 4714 can, for example, reduce manufacturingcomplexity, provide strength to a joint between the snare structure 4712and valvulotome structure 4714, etc. In some implementations, the snarestructure 4712 and the valvulotome structure 4714 may be separatelyformed an coupled together. Separately formed snare structure 4712 andvalvulotome structure 4714 can, for example, provide flexibility inmaterials, provide flexibility in manufacturing methods (e.g., differentcutting or shape-setting methods, independent creation to increasethroughput), etc. The cutting snare system 4710 may be tracked over aguidewire (e.g., with an outer sheath 4718) or tracked through a lumenof a catheter (e.g., the catheter acting as the outer sheath 4718). Thesnare structure 4712 and/or the valvulotome structure 4714 can have thesame or similar features to the other snare structures and valvulotomestructures described herein, for example cells 4713 configured tocapture a guidewire, cutting blades 4716, etc.

In some implementations, the snare structure 4712 can be captured in anouter sheath 4718, leaving the valvulotome structure 4714 expanded, whenthe valvulotome structure 4714 is proximally retracted to cut valves. Insome implementations, the snare structure 4712 can be at least partiallyout of the outer sheath 4718 when the valvulotome structure 4714 isproximally retracted to cut valves. In some implementations, the cuttingsnare system 4710 can be used solely as a valvulotome, for example byonly expanding the valvulotome structure 4714 (e.g., as shown in FIG.47Bii).

The snaring structure 4712 has a first outer diameter and thevalvulotome structure 4714 and/or the blades 4716 have a second outerdiameter. In some examples, the second outer diameter is less than thefirst outer diameter, which can allow the snaring structure 4712 toappose sidewalls of the second vessel without the cutting blades 4716cutting the sidewalls of the second vessel. Where cutting of valves inthe second vessel is desired, the valves extend into the second vesseland are able to be cut by the cutting blades 4716.

FIGS. 47Ci-47Ciii are side views of another example cutting snare system4720. FIG. 47Civ is a side view of yet another example cutting snaresystem 4721. The cutting snare system 4720, 4721 comprises a snarestructure 4722 and a valvulotome structure 4724 configured to be inseries. The valvulotome structure 4724 may telescope inward of the snarestructure 4722 (e.g., as illustrated in FIG. 47Ci). The snare structure4722 may telescope inward of the valvulotome structure 4724 (e.g., asillustrated in FIG. 47Civ). The cutting snare system 4720, 4721 may betracked over a guidewire (e.g., with an outer sheath 4728) or trackedthrough a lumen of a catheter (e.g., the catheter acting as the outersheath 4728). FIG. 47Cii shows the snare structure 4722 and thevalvulotome structure 4724 sheathed in the outer sheath 4728 fortracking over a guidewire and/or through a catheter. The snare structure4722 and/or the valvulotome structure 4724 can have the same or similarfeatures to the other snare structures and valvulotome structuresdescribed herein, for example cells 4723 configured to capture aguidewire, cutting blades 4726, etc.

In some implementations, the snare structure 4722 can be at leastpartially out of the outer sheath 4728 when the valvulotome structure4724 is proximally retracted to cut valves. In some implementations, thecutting snare system 4720, 4721 can be used solely as a valvulotome, forexample by only expanding the valvulotome structure 4724 through the forthe cutting snare system 4720 (e.g., as shown in FIG. 47Ciii) and/or bynot expanding the snare structure 4722 for the cutting snare system4721.

In the cutting snare system 4720, the snaring structure 4722 has a firstouter diameter and the valvulotome structure 4724 and/or the blades 4726have a second outer diameter. In some examples, the second outerdiameter is less than the first outer diameter, which can allow thesnaring structure 4722 to appose sidewalls of the second vessel withoutthe cutting blades 4726 cutting the sidewalls of the second vessel.Where cutting of valves in the second vessel is desired, the valvesextend into the second vessel and are able to be cut by the cuttingblades 4726.

In the cutting snare system 4721, the snaring structure 4722 has a firstouter diameter and the valvulotome structure 4724 and/or the blades 4726have a second outer diameter. In some examples, the second outerdiameter is greater than the first outer diameter, which can allow thesnaring structure 4722 to appose sidewalls of the second vessel, forexample when the valvulotome structure 4728 is in the outer sheath 4728and cannot cut the sidewalls of the second vessel. Where cutting ofvalves in the second vessel is desired, the valves extend into thesecond vessel and are able to be cut by the cutting blades 4726. Thesecond diameter being greater than the first diameter can allow thecutting blades 4726 to cut more of the valve.

FIGS. 47Di-47Dv are side views of still another example cutting snaresystem 4730. The cutting snare system 4730 comprises a snare structure4732 shown in FIG. 47Di and a valvulotome structure 4734 shown in FIG.47Dii. The snare structure 4732 and/or the valvulotome structure 4734can have the same or similar features to the other snare structures andvalvulotome structures described herein, for example cells 4733configured to capture a guidewire, cutting blades 4736, etc. The snarestructure 4732 and/or the valvulotome structure 4734 may include anatraumatic distal tip, for example a tapered nose.

The outer sheath 4738 can be left in place, for example after anotherprocedure described herein. The cutting snare system 4730 may be trackedthrough a lumen or multiple lumens of a catheter 4738, which acts as anouter sheath for the cutting snare system 4730. FIG. 47Div shows thesnare structure 4732 extending out of the distal end of the outer sheath4738. The snare structure 4732 can snare a guidewire, for example asdescribed herein. In some implementations, the snare structure 4732 issized so that the snare structure 4732 and a captured guidewire can beproximally retracted out of the proximal end of the outer sheath 4738.FIG. 47Dv shows the valvulotome structure 4734 extending out of thedistal end of the outer sheath 4738. The valvulotome structure 4732 canbe proximally retracted in the direction 4737 to cut valves, for exampleas described herein.

FIGS. 47Ei-47Eiii are side views of still yet another example cuttingsnare system 4740. FIG. 47Eiv is a side view of another example cuttingsnare system 4741. The cutting snare system 4740 comprises a snarestructure 4742 and an expandable member 4744 radially inward of thesnare structure 4742. The cutting snare system 4740 may be tracked overa guidewire (e.g., with an outer sheath 4748) or tracked through a lumenof a catheter (e.g., the catheter acting as the outer sheath 4748).

The snare structure 4742 can have the same or similar features to theother snare structures described herein, for example cells 4743configured to capture a guidewire, etc. The snare structure 4742 mayinclude an atraumatic distal tip, for example a tapered nose. Theexpandable structure 4744 comprises, for example, a balloon and/or aplurality of expandable wires. In some implementations, the expandablestructure 4744 is coupled to the snare structure 4742 (e.g., as shown inFIGS. 47Ei-47Eiii). This can, for example, help to ensure alignment ofthe snare structure 4742 and the expandable structure 4744 when applyinga cutting force, as described below. In some implementations, theexpandable structure 4744 is separate from the snare structure 4742(e.g., as shown in FIG. 47Eiv). This can, for example, allow more spacefor a guidewire during snaring, allow the use of various types ofexpandable members (e.g., selected for a particular vessel), etc.

The outer sheath 4748 can be left in place, for example after anotherprocedure described herein. The cutting snare system 4740 may be trackedthrough a lumen or multiple lumens of a catheter 4748, which acts as anouter sheath for the cutting snare system 4740. FIG. 47Eii shows thesnare structure 4742 extending out of the distal end of the outer sheath4748. The snare structure 4742 can snare a guidewire, for example asdescribed herein. In some implementations, the snare structure 4742 issized so that the snare structure 4742 and a captured guidewire can beproximally retracted out of the proximal end of the outer sheath 4748.After the cutting snare system 4740 has been proximally retracted out ofthe proximal end of the outer sheath 4748, the cutting snare system 4740may be reinserted into the outer sheath 4748 (e.g., as illustrated inFIG. 47Eiii) and/or over a guidewire. In some implementations, aseparate cutting snare system 4740 may be inserted into the outer sheath4748 and/or over a guidewire.

FIGS. 47Eii and 47Eiii show the cutting snare system 4740 extending outof the distal end of the outer sheath 4748. In some implementations, thecutting snare system 4740 is across a valve (e.g., in a vein). In FIG.47Eii, the expandable structure 4744 is partially expanded (e.g.,inflated) within the snare structure 4742. In FIG. 47Eiii, theexpandable structure 4744 is further expanded (e.g., inflated) withinthe snare structure 4742 until the expandable structure 4744 applies aradially outward force, as indicated by the arrows 4747, to the snarestructure. The force can press the struts or mesh of the snare structure4742 into valve leaflets, which can cut the valve leaflets and/ordisable the valve.

The amount of expansion pressure may be related to the sharpness oraggressiveness of the cutting mechanism (e.g., blade, wire, etc.). Theexpansion pressure may be between about 4 atm (approx. 405 kPa) andabout 20 atm (approx. 2,026 kPa) (e.g., about 4 atm (approx. 405 kPa), 7atm (approx. 709 kPa), 10 atm (approx. 1,013 kPa), 15 atm (approx. 1,520kPa), 20 atm (approx. 2,026 kPa), ranges between such values, etc.).Pressures higher and lower than those listed may be possible dependingon the cutting mechanism.

Lower pressure may be useful for sharp, aggressive cutting blades. Insome examples, a lower pressure balloon with a more aggressive bladepotentially has the advantage of cutting the valve while causing lesstrauma to the surrounding vessel tissue. In the initial contact of theblades with the valve, force is localized at the blade. The sharper theblade, the less force required. As the balloon engages the wall, thelower force is maintained, causing less distention to the vein.

Higher pressure may be useful for a mild cutting wire or no wire at all.In some examples, the mechanical properties of the valve tissue make thevalve very resistant to traditional balloons. A higher-pressure balloon(e.g., cutting or not) can exert more force that might be needed todefeat the valve. Blades on a cutting balloon may initiate a cut, butthe balloon can further propagate these cuts. Higher force may enablegreater propagation of the cut, more effectively disabling the valve.

The expandable member 4744 can be deflated or reduced, and the cuttingsnare system 4740 can be moved, for example to extend across a secondvalve. The expandable structure 4744 can be again expanded (e.g.,inflated) to disable the second valve. The process may be repeated foras many valves as are desired to be disabled.

FIGS. 47Fi and 47Fii are side views of yet another example cutting snaresystem 4750. The cutting snare system 4750 comprises a structure 4752that can snare a guidewire in a first state and/or a second state andcut valves in the second state. FIG. 47Fi shows the structure 4752 inthe first state, in which the structure 4752 has a generally oval form.The structure 4752 can snare a guidewire, for example as describedherein, in the first state.

FIG. 47Fii show the structure 4752 in the second state, in which thestructure 4752 includes proximal cutting elements 4754. The structure4752 in the second state can cut valves, for example as describedherein. The structure 4752 in the second state can snare a guidewire,for example as described herein. In certain implementations, thestructure 4752 can cut valves while the structure 4752 is proximallyretracted with a snared guidewire. In some implementations, theguidewire may be snared with the structure 4752 in the first state, andthe structure 4752 may be reinserted to cut the valves in the secondstate.

In some implementations, the structure 4752 can change from the firststate to the second state by applying a longitudinal force 4755 to thestructure 4752, for example proximally retracting a distal end of thestructure 4752 relative to a proximal end of the structure. Other forcesare also possible. For example, twisting or torqueing forces, use oftemperature induced martensite, etc.

FIGS. 47Gi-47Giii are side views of still another example cutting snaresystem 4760. The snare cutting system 4760 may comprise a snarestructure 4762 and a valvulotome structure 4764 in series, for exampleas shown in the cutting snare system 4721 of FIG. 47Civ. The snarestructure 4762 and/or the valvulotome structure 4764 can have the sameor similar features to the other snare structures and valvulotomestructures described herein, for example cells configured to capture aguidewire, cutting blades, etc.

In FIG. 47Gi, the snare structure 4762 and valvulotome structure 4764are collapsed inside the outer sheath 4768. In FIG. 47Gi, the snarestructure 4762 has been distally advanced relative to the outer sheath4768. The snare structure 4762 can snare a guidewire, for example asdescribed herein.

The snare cutting system 4760 comprises an outer sheath 4768 comprisinga plurality of elongate apertures 4765. In FIGS. 47Gii, the valvulotomestructure 4764 is visible through the apertures 4765. In FIG. 47Giii,the valvulotome structure 4764 has been rotated relative to the outersheath 4768 such that the struts of the valvulotome structure 4764 canlaterally extend from an intermediate portion of the outer sheath 4768proximal to the distal end of the outer sheath 4768, as shown in FIG.47Giii. The valvulotome structure 4764 can be proximally retracted inthe direction 4767 to disable valves, for example as described herein.

The procedures described herein generally divert blood from a firstcavity (e.g., an occluded artery) to a second cavity (e.g., the lateralplantar vein). In some circumstances, a user may desire to divert bloodinto a different second cavity than the lateral plantar vein. Forexample, the lateral plantar vein may be perforated (e.g., due to usefor a previous surgical bypass procedure), may be occluded (e.g., due tothrombosis and/or stenosis), may be too far from the first cavity, etc.Blood generally flows from high pressure to low pressure along anyavailable return path, so blood may bypass certain restricted areas,whereas the blood would preferably pass through and/or dwell inextremities. Procedures described herein can include providingretrograde blood flow through a plurality of vessels.

Occlusions and stenoses in the peripheral arterial system can inhibit orprevent oxygenated blood from reaching the distal limbs/extremities suchas the hands and feet. Reduction in peripheral arterial blood flow canimpede the body's ability to heal wounds in these areas, and mayultimately result in partial or full amputation of the limb.Arterialization of the venous system, for example as described herein,can allow for oxygenated (normally arterial) blood to reach the distallimb to heal wounds and reduce the risk of amputation. FIG. 48Aillustrates an example image of a foot after a venous arterializationprocedure. Blood can be seen flowing around major vessels of the foot.Merely establishing a venous circuit with retrograde arterial blood flowmay not be enough to drive wound healing.

The quality/performance of the retrograde circuit can be an importantconsideration, for example including its ability to achieve perfusion ofoxygenated arterial blood into the most distal regions of the limb(e.g., forefoot, toes, heel), where wounds are typically present.Achieving distality of blood flow is typically needed for wound healing.If a circuit has been established that has robust flow, the flow mayfail to reach the most distal vessels, for example because the bloodwill tend to return via the “path of least resistance.” Methods anddevices that allow the establishment of “high quality” retrograde venouscircuits in a controlled and planned manner can enable adequateperfusion of the distal limb to heal wounds more effectively and furtherreduce the risk of amputation. A limb can include an arm and a distallimb could include a hand and/or fingers.

Perfusion in retrograde venous arterialization is a complex function of,for example, blood flow rate, flow volume, pressure, anatomy, physicalproperties of tissue/blood (e.g., viscosity, etc.), and/or the physicalgeometry of the circuit (e.g., number of inflow and outflow pathways,size/caliber of the vessels, etc.). Modification of a single or multiplevariables may influence one or more other variables, which in turn mayincrease or decrease the circuit's ability to adequately perfuse bloodto the target wound.

An example method of causing perfusion in the retrograde venous circuitis to increase pressure in the circuit by reducing the blood's abilityto simply “shunt” back to the venous return to the heart. For example,the embolization of specific “blood-stealing” outflow veins (e.g., sidebranches) can close off these return veins. Because retrograde bloodcannot quickly find a low pressure (low resistance) return pathway, itis forced to move distally, into the small vessels responsible forfeeding tissue near the limb surface, where wounds occur. For a givenflow rate, reducing the number of outflow vessels will generallyincrease the pressure in the circuit, increasing the likelihood ofdistal perfusion. A similar effect can be accomplished via a coveredgraft, flow-diverting stent, etc. Improving distal perfusion couldenhance collateralization and/or neoangiogenesis, which can furtherimprove distal perfusion, for example in the long term.

FIG. 48B illustrates another example image of a foot after a venousarterialization procedure. Compared to FIG. 48A, blood can be seenflowing to many more vessels. Blood flow to more vessels, particularlyin an extremity like the foot, can help with wound healing and reducethe risk of amputation. Certain methods described herein can achieveblood flow in all circuits in all veins, including deep and superficialveins. The retrograde flow can start at any peripheral artery, forexample as high as the femoral system, continue throughout the tibialsystem, and continue distal in the foot. For example, the veins that canbe claimed by retrograde flow can include greater veins including theirredundant veins (e.g., posterior tibial vein, anterior tibial vein,great saphenous vein, small saphenous vein), veins distal to the greaterveins and their redundant veins (e.g., lateral plantar vein, lateralmarginal vein, medial plantar vein, medial marginal vein, fibular veins,dorsal arcade of the foot, dorsal vein of the Hallux), and perforatorveins and their redundant veins that connect the upper and lower veinnetworks of the foot (e.g., medial foot perforators (inframalleolar,navicular/scaphoid, cuneal), lateral foot perforators (intertendinous,subtendinous), and calcaneal foot perforator). In some implementations,blood can flow to some, a majority, or all of these veins.

FIG. 49 illustrates an example method of providing blood flow to aplurality of veins. In an original procedure, blood from an occludedposterior tibial artery was diverted into a medial plantar vein 4407through a fistula prosthesis (e.g., as described herein). Blood was ableto flow from the medial plantar vein 4407 to the anterior tibial vein4468. In a second procedure several weeks after the first procedure, aloop 4800 was established from the medial plantar vein 4407 to thelateral plantar vein 4408 (e.g., by disabling valves that wouldotherwise inhibit or prevent flow therebetween). The lateral plantarvein 4408 was accessed downstream of an occlusion therein. A stent waspositioned downstream of the fistula in the lateral plantar vein,although the stent could be positioned in any vessel in the retrogradeflow circuit for this purpose.

The stent kept the vessel open and patent. The stent kept the valves inthe vessel open to permit retrograde flow. prosthesis to help maintain aflow deep in the foot, for example by propping open valves. The stentwas a paclitaxel-eluting stent (ELUVIA™ available from BostonScientific), although other drug eluting stents, bare metal stents(e.g., SUPERA®, available from Abbott Vascular), stent-grafts, polymerstents, etc. could also be used. Preferably, the stent can handle thedynamic ankle bend. The stent optionally inhibits or prevents perfusionthrough sidewalls to or from branch vessels (e.g., by including a graft,having a low porosity such as a flow diverter, etc.). The stent may besmall (e.g., 5 Fr, 4 Fr, 3 Fr, or even smaller (e.g., a 3 Fr or 4 Frwoven stent or a 4 Fr or 5 Fr laser cut stent)). The diameter of thestent could be, for example, between about 2 mm and about 6 mm (e.g.,about 2 mm, about 3 mm, about 4 mm, about 5 mm, about 6 mm, rangesbetween such diameters, etc.).

Retrograde flow in the combination of the medial plantar vein 4407 andthe lateral plantar vein 4408, which included a vessel on each side ofthe loop 4800, led to greater perfusion of the arch and the distal footthan either a circuit with only the medial plantar vein or the lateralplantar vein could achieve alone, as blood was forced to flow distallythrough a collateral network. Without being bound by any particulartheory, it is believed that blood was forced to return to the heart viathe collateral network rather than larger veins. In someimplementations, the lateral plantar vein 4408 could be accessed in theoriginal procedure or after a shorter or longer duration than six weeks.In some implementations, a plurality of fistulas may be formed (e.g.,using the procedures described herein) to cause retrograde flow in aplurality of veins. Preferably, the plurality of veins includes one veinon each side of the dorsal venous arch 4454.

In some implementations, retrograde oxygenated blood flow has beenestablished in one or more venous circuits via venous arterialization(e.g., as described herein). Additional methods may be used to furtherdirect flow to specific regions of the foot to increase perfusion.

Some methods can include creating a fistula between a first vessel(e.g., an artery) and a second vessel (e.g., a vein) in the foot (e.g.,as opposed to above the ankle), for example using techniques describedherein. In the venous system, a plurality of vessels transmit blood backto the heart. The system includes copious redundancy, manyinterconnections, bifurcations, and confluences. The venous system is a“low pressure” system, as opposed to the higher pressure arterialsystem. When pressurizing the venous system with arterial blood flow,the blood will take the path of least resistance (e.g., to outflowvessels connected to the low-pressure return, where there are no valvesto block flow). Many of these return vessels are proximal to a desiredblood path in the distal limb or extremity, and therefore “steal” bloodaway from the intended target. By terminating one, some, or all of thesevessels, flow can be directed and/or pressure can be increased to helpincrease distal perfusion in a controlled manner.

Some methods can include limiting and/or adjusting an outflow in thevenous system (e.g., limiting vessel steal or shunting of blood). Forexample, a stent or stent graft can channel blood past stealing vessels.For another example, bifurcating veins or side branches can be embolized(e.g., via coils, microspheres, liquid embolics, laser, etc.). FIG. 50illustrates a method of using embolization coils 5002 to prevent vesselsteal and redirect blood distally, as annotated by the arrow 5004, whichindicates a direction of oxygenated blood flow.

Some methods can include physically directing the retrograde, oxygenatedblood into multiple target veins instead of a single target vein (e.g.,as described above with respect to FIG. 49 ). For example, valves can bedisabled (e.g., using a valvulotome, balloon, stent, etc.) in more thanone vein. Distal pedal access as described herein may help with suchdisabling by providing access to all of the desired veins includingvalves to be disabled. Valvulotomes as described herein may help withsuch disabling by allowing ablation during distal advancement and/orduring advancement or retraction. For another example, multiple venousarterializations can be performed to direct the flow of oxygenated bloodfrom two or more arteries into two or more veins, for example one oreach using methods described herein. For another example, an increase inpressure in the venous system is able to overcome resistance of thevalves, which can aid in perfusion when the pressure increase occurs inveins extending to the distal extremity (e.g., foot, hand, toes,fingers).

Some methods can include applying external pressure (e.g., cuff,tourniquet, wrap) to increase blood pressure in the foot by limitingvenous outflow, for example because blood has nowhere to go but distal.The pressure application can be continuous or intermittent. Combinationsof these methods are possible, and other methods are possible.

Certain fistula prostheses described herein are configured to direct100% or all of the fluid from a first vessel into a second vessel. Sucha configuration may be most suitable, for example, for treatment of anartery having chronic total occlusion in which the prosthesis ispositioned proximate to the occlusion, as anything downstream of theocclusion was likely already occluded. In some circumstances, the arteryis not totally occluded, can be at least partially opened, treatmentincludes placement of the prosthesis well upstream of the occlusion suchthat healthy branch arteries still providing some benefit might bestarved of blood or “jailed,” and/or “vessel steal” reduces flow toother vessels. Placement up stream can be the result of a diseased orcalcified artery being difficult to cross (e.g., due to calcification,due to compromised and/or poor inflow, etc.) and/or stent. Fluid movesfrom high pressure to low pressure, so when a high pressure artery isconnected to a low pressure vein, blood may have a tendency to flow tothe vein, which can compromise or “steal” the amount of blood that flowsto other arteries (e.g., peroneal artery). Reduced blood flow in otherarteries may cause ischemia and/or pain in anatomy supplied by thevessels having blood stolen therefrom.

Allowing at least some blood to continue to flow in the first vessel, ordistal arterial flow preservation, may provide one or more advantages.For example, intentionally placing the prosthesis upstream of anocclusion can allow the crossing and stenting in the first vessel to bein a healthier portion of the first vessel (e.g., little to nocalcification, good inflow, etc.) and/or a portion of the first vesselthat may be easier to cross into the second vessel. Freedom of placementposition can provide significant flexibility to a user. For anotherexample, blood can continue to flow to downstream branch vessels canmaintain the existing arterial network, such as maintaining the benefitof those branch vessels. For yet another example, vessel steal can beinhibited or prevented because the blood can continue to flow in thearterial system. Ischemia and/or pain caused from stolen blood might beavoided. For another example, interventional procedures (e.g., plain,drug eluting, and/or scoring angioplasty, atherectomy, PTA, etc.) may beperformed downstream of the prosthesis and/or in conjunction with theprocedure, allowing percutaneous crossing to be further used asadjunctive therapy with more traditional treatments. Venousarterialization may be performed on a larger class of subjects. Forexample, while Rutherford Class 5 or 6 patients typically have acritical limb ischemia or chronic total occlusion, Rutherford Class 3 or4 (or lower) patients may have peripheral artery disease or claudicationthat only partially occludes an artery. In contrast to other so-calledfenestrated stent grafts, such as descending aortic stent grafts withspecific cutouts for connecting additional stent grafts to formartificial branch arteries to, for example, the kidneys, or such asaortic stent grafts with specific cutouts to permit perfusion to vesselscarrying blood to the head or arms, the windows of the fenestrated stentgrafts described herein permit perfusion to continue to the distalparent, and the blood flowing through the main lumen of the fenestratedstent graft is diverted into a second vessel different than the parent.

FIG. 51A is a partial cross-section of an example device 5100 providingfluid flow from a first vessel 5101 to a second vessel 5102 and throughthe first vessel 5101. The first vessel 5101 is at least partiallyoccluded. The first vessel 5101 may comprise an artery (e.g., aperipheral artery such as a tibial artery) and the second vessel 5102may comprise a vein (e.g., a peripheral vein such as a tibial vein). Thedevice 5100 allows at least some blood to continue to flow in the firstvessel 5101, and may provide one or more of the distal arterial flowpreservation advantages described herein.

The device 5100 comprises a first section 5104 and a second section5106. The first section 5104 generally abuts or partially overlaps thesecond section 5106. The device 5100 may comprise a radiopaque marker5107 showing a transition 5105 between the first section 5104 and thesecond section 5106. The marker 5107 may be, for example, swaged,electroplated, a threaded wire, a band, change in strut pattern, changein cell structure, etc.

The first section 5104 comprises a stent structure 5108. The stentstructure 5108 may comprise woven and/or knitted wires, cut struts,combinations thereof, etc. The first section 5104 comprises pores orapertures 5103 that allow blood to flow into the proximal end of thestent structure 5108 into the stent structure 5108, and then from insidethe stent structure 5108 to outside the stent structure 5108, anddownstream in the first vessel 5101, as indicated by the arrow 5112. Thestent structure 5108 is configured to anchor the first section 5104 inthe first vessel 5101. The first section 5104 may comprise a radiopaquemarker, for example at the proximal end of the first section 5104. Thedevice 5100 may comprise an additional section proximal to the firstsection 5104.

The second section 5106 comprises the stent structure 5108 and acovering or graft 5109. The stent structure 5108 may be the same ordifferent (e.g., having at least one parameter that is different (e.g.,cell structure, density, porosity, material, dimensions such asdiameter, thickness, and/or length), etc.) between the first section5104 and the second section 5106, and/or within the first section 5104and/or the second section 5106. The second section 5106 may be integralor monolithic with the first section 5104. The graft 5109 of the secondsection 5106 is configured to provide a fluid flow passage from thefirst vessel 5101 to the second vessel 5102, as indicated by the arrow5110. Blood can flow through the second vessel 5102 as described herein.The graft 5109 preferably does not comprise pores configured to allowblood flow from inside to outside. The stent structure 5108 isconfigured to anchor the first section 5106 in the second vessel 5102.The second section 5106 may comprise a radiopaque marker, for example atthe distal end of the second section 5106. The device 5100 may comprisean additional section distal to the second section 5106. The proximalend of the graft 5109 may be generally perpendicular to a longitudinalaxis of the device 5100, which could provide ease of manufacturingand/or deployment (e.g., because rotational orientation does notmatter). The proximal edge of the graft 5109 may include a pattern, forexample straight, angled, scalloped, eccentric, etc.

FIG. 51B is a side view of another example device 5120 providing fluidflow from a first vessel 5101 to a second vessel 5102 and through thefirst vessel 5101. The device 5120 allows at least some blood tocontinue to flow in the first vessel 5101, and may provide one or moreof the distal arterial flow preservation advantages described herein.The device 5120 may share several of the features of the device 5100(e.g., first section 5124, second section 5126, stent structure 5128,graft 5129, etc.). The transition 5125 of the device 5120 is notgenerally perpendicular, but is at an angle α, to the longitudinal axisof the device 5120. The angle α may be measured against a sidewall(e.g., as shown in FIG. 51B), which may be an easy measurement becausethere is solid material forming both sides of the angle α. The angle αmay be measured against an artificial longitudinal axis extendingthrough the device 5120, which may be an easy measurement when sidewallsof the device 5120 are tapered in the transition 5125. The angle α maybe, for example, between about 10° and about 70° (e.g., about 10°, about20°, about 30°, about 40°, about 50°, about 60°, about 70°, rangesbetween such values, etc.). Higher and lower angles α are also possible,for example for indications in which the second vessel 5102 is close tothe first vessel 5101 or far from the first vessel 5101, respectively.The angled transition 5125 may provide better continued flow through thefirst vessel 5101, as indicated by the arrow 5112, because less of thefirst vessel 5101 is occluded. Deploying the device 5120 may compriserotationally orienting the device 5120, for example in the orientationshown in FIG. 51B. The device 5120 may comprise a first radiopaquemarker 5127 a at the proximal-most point of the transition 5125 and asecond radiopaque marker 5127 b at the distal-most point of thetransition 5125, for example because material for the graft 5129 may begenerally radiolucent.

FIG. 51C is a side view of yet another example device 5140 providingfluid flow from a first vessel 5101 to a second vessel 5102 and throughthe first vessel 5101. The device 5140 allows at least some blood tocontinue to flow in the first vessel 5101, and may provide one or moreof the distal arterial flow preservation advantages described herein.The device 5140 may share several of the features of the device 5100(e.g., first section 5144, second section 5146, stent structure 5148,graft 5149, etc.). The stent structure 5148 may be the same or different(e.g., having at least one parameter that is different (e.g., cellstructure, density, porosity, material, dimensions such as diameter,thickness, and/or length), etc.)) between the first section 5144 and thesecond section 5146, and/or within the first section 5144 and/or thesecond section 5146. In some implementations, the second section 5146may lack a stent structure.

The first section 5144 and the second section 5146 of the device 5140are separate and deployed sequentially. For example, the first section5144 may be deployed first and the second section 5146 may be deployedsecond, with the distal segment of the first section 5144 radiallyoutward of the proximal segment of the second section 5146. The firstsection 5144 can establish structural support for the fistula. Foranother example, the second section 5146 may be deployed first and thefirst section 5144 may be deployed second, with the distal segment ofthe first section 5144 radially inward of the proximal segment of thesecond section 5146. The first section 5144 can help prop open thefistula, provide radial outward pressure on the segment of the secondsection 5166 that overlaps with the first section 5144, and/or reduceturbulence effects that otherwise might be caused by the proximal end ofthe second section 5146. At least one of the first section 5144 or thesecond section 5146 may comprise an anchor configured to inhibit orprevent relative movement between the first section 5144 and the secondsection 5146 after deployment. For example, the anchors may includeradially-outward protrusions, hooks, barbs, detents, etc., which may bein the stent structure 5148 or attached to the first section 5144 and/orthe second section 5146. In some implementations, the anchors maycomprise a ratchet. For example, the the first section 5144 and thesecond section 5146 may be relatively longitudinally and/or rotationallymoved relative to each other, for example segment-by-segment, untillocked im place. Anchors may facilitate orientation of the device 5140(e.g., only being anchored when properly oriented). The anchor mayinteract with the other of the first section 5144 and/or the secondsection 5146 and/or may interact with the first vessel 5101, the secondvessel 5102, and/or interstitial tissue. Limiting relative movement canhelp to maintain the graft 5149 boundary to ensure that the first vessel5101 is not jailed. The device 5140 may provide a user with ease ofdeployment. For example, the first section 5144 can be comfortablydeployed to support the first vessel 5101 without much accuracy. Then,the second section 5146 can be deployed using a more accurate deploymentsystem to hit the target (e.g., the proximal end hitting an edge of thefirst vessel 5101) to ensure that the first vessel 5101 is not jailed.

The first section 5144 anchors in the first vessel 5101, extends throughinterstitial tissue, and into the second vessel 5102. The second sectionextends from at least partially in the first vessel 5101, throughinterstitial tissue, and anchors in the second vessel 5102. At leastsome segment of the first section 5144 does not overlap with the secondsection 5146. The non-overlapping segment of the first section 5144 isfree from graft material, which allows blood to continue to flow in thefirst vessel 5101, as shown by the arrow 5112. The second section 5146allows blood to flow into and through the second vessel 5102, as shownby the arrow 5110. The proximal end of the graft 5149 of the secondsection 5146 may be substantially perpendicular (e.g., as shown in FIG.51C), or may be angled (e.g., like the graft 5129 described with respectto the device 5120). The proximal and/or distal ends of the firstsection 5144 and/or the second section 5146 may comprise a radiopaquemarker 5147, for example to help a user determine an anchoring position,an amount of overlap, a rotational orientation, etc.

FIG. 51D is a side view of still another example device 5160 providingfluid flow from a first vessel to a second vessel and through the firstvessel. The device 5160 allows at least some blood to continue to flowin the first vessel, and may provide one or more of the distal arterialflow preservation advantages described herein. The device 5160 may shareseveral of the features of the devices 5100, 5120 (e.g., first section,second section, stent structure, graft 5169, etc.). Only the graft 5169is shown in FIG. 51D for simplicity. The graft 5169 includes a cutout5168 where the device 5160 does not include the graft 5169 such that thestent structure is bare. The percentage of bare circumference isvariable along the length of the device 5160, for example a V-shapedcutout 5168 (e.g., as shown in FIG. 51D) that reduces from a firstpercentage (e.g., about 50%) of bare stent structure to a secondpercentage (e.g., about 10%) of bare stent structure less than the firstpercentage as the device 5160 extends distally. A lower percentage maybe advantageous for orienting the device 5160. The percentage generallyrelates to the flow resistance through the first vessel. In anatomywhere more flow is desired (e.g., proximal or upstream in the firstvessel (e.g., closer to the groin)), the percentage may be higher sothat more blood can flow to the larger and/or more numerous vesselsdownstream. In anatomy where less flow is desired (e.g., distal ordownstream in the first vessel (e.g., closer to the foot)), thepercentage may be lower so that more blood can flow to the secondvessel.

In general, the cutout 5169 of the device 5160 can be at least partiallydefined using a few variables that describe the opening in the covering:the angle 5162 from proximal to distal; the length 5164; the width 5166at the proximal end of the cutout 5169; and/or the width 5167 at thedistal end of the cutout 5169. These variables can be adjusted or tunedto correspond to any overall shape, with other features (such asscallops) possible at a more detailed level. The device 5169 can includeas many cutouts as desired, at any length along the device 5160.

FIG. 52A is a side view of still another example device 5200 providingfluid flow from a first vessel 5101 to a second vessel 5102 and throughthe first vessel 5101. The device 5200 allows at least some blood tocontinue to flow in the first vessel 5101, and may provide one or moreof the distal arterial flow preservation advantages described herein.The device 5200 comprises a first section 5204 and a second section5206. The first section 5204 at least partially longitudinally overlapsthe second section 5206. In some examples, the proximal end and/ordistal end of the first section 5204 is substantially longitudinallyaligned with the respective proximal and/or distal end of the secondsection 5206. Each of the first section 5204 and the second section 5206anchors in each of the first vessel 5101 and the second vessel 5102. Theproximal and/or distal ends, and/or other parts (e.g., a longitudinalcenter), of the first section 5204 and/or the second section 5206 maycomprise a radiopaque marker 5207.

The first section 5204 comprises a stent structure 5208, for examplelike the stent structure 5108. The first section 5204 comprises pores orapertures 5203 that allow blood to flow into the proximal end and/orthrough the pores 5203 of the stent structure 5208 into the stentstructure 5208, and then flow from inside the stent structure 5208 tooutside the stent structure 5208, and downstream in the first vessel5101, as indicated by the arrow 5112. As described herein, only thefirst section 5204 may comprise the stent structure 5208 or the both thefirst section 5204 and the second section 5206 may comprise the stentstructure 5208.

The second section 5206 comprises a covering or graft 5209 andoptionally the stent structure 5208. In embodiments comprising the stentstructure 5208, the stent structure 5208 may be the same or different(e.g., having at least one parameter that is different (e.g., cellstructure, density, porosity, material, dimensions such as diameter,thickness, and/or length), etc.) between the first section 5204 and thesecond section 5206, and/or within the first section 5204 and/or thesecond section 5206. The graft 5209 of the second section 5206 isconfigured to provide a fluid flow passage from the first vessel 5101 tothe second vessel 5102, as indicated by the arrow 5110. Blood can flowthrough the second vessel 5102 as described herein. The graft 5209preferably does not comprise pores configured to allow blood flow frominside to outside.

The second section 5206 may be integral or monolithic with the firstsection 5204. The first section 5204 and the second section 5206 may bedeployed at substantially the same time. The first section 5204 may beseparate from the second section 5206 such that they may be deployedsubstantially simultaneously or at least partially separately. In someimplementations, the stent structure may have a figure-8 cross section,in which the first section 5204 comprises the top half of the 8 and thesecond section 5206 comprises the bottom half of the 8. In someimplementations, the stent structure 5208 may form a lumen and the graft5209 may extend across the lumen, forming two flow paths: a first porousflow path through the first section 5204 and a second nonporous flowpath through the second section 5206. Because both the first section5204 and the second section 5206 extend into the second vessel 5102,positioning of the device 5200 may be simplified, for example becauserotational orientation generally does not affect function, although auser may prefer that the second section 5206 be adjacent to the secondvessel 5102. The inventors have discovered that, surprisingly, someblood flow access to interstitial tissue does not negate the benefitsprovided by the fistula.

FIG. 52A may provide partially-circumferential fenestration, in which acertain percentage of the circumference of the stent structure 5208 isbare (not covered by the graft 5209). FIG. 52A illustrates the entirelength of the device 5200 including the graft 5209. In some examples,only a partial length of the device 5200 includes the graft 5209 (e.g.,the proximal segment being bare). In some examples, only a partiallength of the device 5200 includes the graft 5209 being partiallycircumferential (e.g., the proximal segment being partiallycircumferential) while the remainder of the device 5200 includes a fullycircumferential graft 5209. The percentage of bare circumference may be,for example, between about 5% and about 75% (e.g., about 5%, about 10%,about 20%, about 30%, about 40%, about 50%, about 60%, about 75%, rangesbetween these values, etc.).

FIG. 52Bi is a side view of still yet another example device 5220providing fluid flow from a first vessel 5101 to a second vessel 5102and through the first vessel 5101. The device 5220 allows at least someblood to continue to flow in the first vessel 5101, and may provide oneor more of the distal arterial flow preservation advantages describedherein. The device 5220 may share several of the features of the device5200 (e.g., first section 5224, second section 5226, stent structure5228, graft 5229, etc.). The first section 5224 does not extend into thesecond vessel 5102. Rather, the first section 5224 terminates in thefirst vessel 5101. In some examples, the proximal end the first section5224 is substantially longitudinally aligned with the proximal end ofthe second section 5226 (e.g., as shown in FIG. 52Bi). In some examples,the proximal end the first section 5224 is not longitudinally alignedwith the proximal end of the second section 5226, for exampleoriginating proximal to the proximal end of the second section 5226 ordistal to the proximal end of the second section 5226. The secondsection 5226 extends through interstitial tissue and into the secondvessel 5102. The diameter of the second section 5226 may change from theproximal end to the distal end, for example like the tapered or angledstents described herein (e.g., having one or more cylindrical portionsand one or more tapered portions).

The first section 5224 optionally comprises pores 5223, for example asdescribed with respect to FIG. 52A. In some implementations, the firstsection 5224 may be devoid of pores, because blood can flow through alumen of the first section 5224 and downstream in the first vessel 5101,as indicated by the arrow 5112. In some implementations, the firstsection 5224 may comprise a simple structure such as one or more ringsor extensions configured to push the second section 5226 against thewall of the first vessel 5101. Blood can flow past the simple structureand downstream in the first vessel 5101.

Because the second section 5226 extends into the second vessel 5102regardless of the position of the first section, positioning of thedevice 5220 may be simplified, for example because rotationalorientation generally does not affect function, although a user mayprefer that the second section 5226 be adjacent to the second vessel5102. The first section 5224 may be integral or monolithic with thesecond section 5226, and they may be deployed at substantially the sametime. The first section 5224 may be separate from the second section5226 such that they may be deployed substantially simultaneously or atleast partially separately.

FIG. 52Bii is an example cross-sectional view of the device 5220 of FIG.52Bi across the line 52Bx-52Bx. As described as a possibleimplementation with respect to FIG. 52A, the first section 5224 and thesecond section 5226 form a figure-8. FIG. 52Bii shows the graft 5229 ofthe second section 5226 inward of the stent structure 5228, although thegraft 5229 may be otherwise coupled to the stent structure 5228, have adifferent stent structure, or be devoid of a stent structure. Althoughshown as generally circular, the cross-sections of the first section5224 and the second section 5226 could be oval or have other shapesconfigured to occupy more of the first vessel 5101 and/or the secondvessel 5102 including, for example, semicircular, polygonal, etc.

FIG. 52Biii is another example cross-sectional view of the device 5220of FIG. 52Bi across the line 52Bx-52Bx. As described as a possibleimplementation with respect to FIG. 52A, the graft 5229 extends across alumen of the stent structure 5228 to form two flow paths.

FIG. 52Ci is a side view of another example device 5230 providing fluidflow from a first vessel 5101 to a second vessel 5102 and through thefirst vessel 5101. The device 5230 allows at least some blood tocontinue to flow in the first vessel 5101, and may provide one or moreof the distal arterial flow preservation advantages described herein.The device 5230 may share several of the features of the devices 5200,5220 (e.g., first section 5234, second section 5236, stent structure5238, graft 5239, radiopaque marker 5237, etc.). Like the device 5220,the first section 5234 does not extend into the second vessel 5102.Rather, the first section 5234 terminates in the first vessel 5101.Distal to the branching of the second section 5234, the first section5234 expands to anchor the first section 5234 in the first vessel 5101.Certain such configurations can provide good anchoring in the firstvessel 5101, for example resisting rotation or other forces.

FIG. 52Cii is a cross-sectional view of the device 5230 of FIG. 52Ciacross the line 52Cii-52Cii. The first section 5234 is crescent or beanshaped around a round shape of the second section 5236. The firstsection 5234 can revert to a round shape distal to the branching of thesecond section 5236. Such a cross section is also a possibleimplementation with respect to the devices 5200, 5210.

FIG. 52D is a side view of yet another example device 5240 providingfluid flow from a first vessel 5101 to a second vessel 5102 and throughthe first vessel 5101. The device 5240 allows at least some blood tocontinue to flow in the first vessel 5101, and may provide one or moreof the distal arterial flow preservation advantages described herein.The device 5240 may share several of the features of the devices 5100,5230 (e.g., the first section 5244 comprising an uncovered stent, thesecond section 5246 comprising a graft, etc.). the first section 5244comprises a tapered portion 5245 configured to narrow from a firstdiameter to a second diameter smaller than the first diameter. Thetapered portion 5245 comprises pores 5243 configured to allow blood toflow around the second section 5406 and continue to flow in the firstvessel 5101, as shown by the arrows 5112. Blood that flows into thesecond section 5246 is diverted into the second vessel 5102, as shown bythe arrow 5110. The device 5240 may provide particular advantages inlarger vessels (e.g., proximal to occlusions before an artery begins tonaturally taper and narrow). The self-centering nature of the device5240 can provide an all-in-one solution for centering the second section5246 in a large vessel to permit flow around the second section 5246,while also gathering some of the flow for the second vessel 5102. Thetapered section 5425 could substantially center the proximal end of thesecond section 5246 in the first vessel (e.g., as shown in FIG. 52D).The tapered section 5425 could push the proximal end of the secondsection 5246 to a side of the first vessel (e.g., a side towards thesecond vessel 5102 (e.g., to reduce occlusion of the first vessel 5101),a side away from the second vessel 5102 (e.g., to reduce a bend angle ofthe second section 5426).

The first section 5424 may be integral with the second section 5426. Forexample, the first section and the second section may share a stentstructure that is covered with graft material distal to the taperedportion 5425. The first section 5424 may be separate from the secondsection 5426 and deployed sequentially. For example, the first section5424 may be deployed in the first vessel 5101 and then the secondsection 5426 may be deployed through the first section 5424 with theproximal end of the second section 5426 overlapping the distal end ofthe first section 5424.

FIG. 53A is a side view of still another example device 5300 providingfluid flow from a first vessel 5101 to a second vessel 5102 and throughthe first vessel 5101. The device 5300 allows at least some blood tocontinue to flow in the first vessel 5101, and may provide one or moreof the distal arterial flow preservation advantages described herein.The device 5300 may share several of the features of the device 5100 ormore particularly the second section 5106 (e.g., stent structure 5308,graft 5309, radiopaque markers 5307, etc.). The graft 5309 extendssubstantially the entire length of the device 5300, although sectionsproximal and distal to the illustrated device 5300 are also possible.The device 5300 comprises windows or fenestrations 5303 lacking thegraft 5309. The graft 5309 may be removed to form the windows 5303, ornot formed in the first place. Manufacturing the device 5300 with thewindows 5303 may simplify a placement procedure (e.g., deploy the device5300 and confirm rotational alignment) and/or reduce risk of creatingthrombus. In some implementations, the device 5300 may comprisecircumferential or spiral slits along at least a segment of the graft5309 such that when the device 5300 bends the slits separate. The device5760 of FIG. 57F is one such example. The graft 5309 may overlap toguard against undesired leakage. A segment comprising the bend in thesecond vessel 5102 is desirably devoid of such slits. Such aconfiguration may further simplify a placement procedure byautomatically opening the windows 5303. The windows 5303 allow blood toflow into the proximal end of the device 5300 into the device 5300, andthen from inside the device 5300 to outside the device 5300, anddownstream in the first vessel 5101, as indicated by the arrow 5112.Blood that does not exit the windows 5303 may flow into and through thesecond vessel 5102, as shown by the arrow 5110. The radiopaque marker5307 may be indicative of a side of the device 5300 comprising thewindow 5303. An edge or outline or sides or ends of the window 5303 maybe marked by a radiopaque marker. The stent structure exposed by thewindow 5303 may be clad with radiopaque material.

FIGS. 53Bi-53Biii illustrate an example method of in situ formation ofan example device 5320 providing fluid flow from a first vessel 5101 toa second vessel 5102 and through the first vessel 5101. The device 5320allows at least some blood to continue to flow in the first vessel 5101,and may provide one or more of the distal arterial flow preservationadvantages described herein. The device 5320 may share several of thefeatures of the device 5300, but is not manufactured with windows orstructure such as slits configured to form windows.

In FIG. 53Bi, a preliminary device 5310 is anchored in the first vessel5101, extends through interstitial tissue, and is anchored in the secondvessel 5102. In this way, the preliminary device 5310 shares manyfeatures with many fistula prostheses described herein, and any suchprostheses may be used as the preliminary device 5310. A guidewire 5312extends through a side of the preliminary device 5310. The guidewire5312 may be navigated from a vasculature access point and puncturethrough the side of the preliminary device 5310. The guidewire may beintegrated with the preliminary device 5310 such that the guidewire 5312already extends through the side of the preliminary device 5310 afterplacement of the preliminary device 5310.

In FIG. 53Bii, an expansion device 5314 (e.g., plain balloon, drugeluting balloon, scoring balloon, expandable filaments, dilator,combinations thereof, etc.) is tracked over the guidewire 5312 andextends through the side of the preliminary device 5310. In someimplementations, a fenestration device such as a laser atherectomy tool(e.g., Turbo Elite®, available from Spectranetics) may be used. Theexpansion device 5314 is radially expanded, as shown by the arrows 5316,to form a large window 5323 (FIG. 53Biii) and making the device 5320 insitu. The window 5323 allows blood to flow into the proximal end of thedevice 5320 into the device 5320, and then from inside the device 5320to outside the device 5320, and downstream in the first vessel 5101, asindicated by the arrow 5112. Blood that does not exit the window 5323may flow into and through the second vessel 5102, as shown by the arrow5110. In some implementations, the expansion device 5314 may comprise adilator tracked over the guidewire 5312. In some implementations, theguidewire 5312 may puncture the side of the preliminary device 5310 toform several small windows, one or more of which may optionally beexpanded.

FIG. 53Ci shows an example cell pattern for a stent structure 5348 of afenestrated device. FIG. 53Cii shows an example of the stent structure5348 of FIG. 53Ci partially covered in graft 5349 and including a window5343. The cell pattern includes a first longitudinal segment 5342, asecond longitudinal segment 5344, and a third longitudinal segment 5346.The first longitudinal segment 5342 comprises a first cell patternconfigured to anchor in a first vessel (e.g., an artery). The secondlongitudinal segment 5344 comprises a second cell pattern configured toanchor in a second vessel (e.g., a vein). The third longitudinal segment5346 is longitudinally between the first longitudinal segment 5346 andthe second longitudinal segment 5344. The third longitudinal segment5346 comprises a third cell pattern configured to be more easilypunctured during a fenestration process. For example, the third cellpattern may be more porous than the first cell pattern and/or the secondcell pattern. In some implementations, the pores of the third cellpattern are sized for a typical angioplasty balloon (e.g., about 1.5 mmto about 5 mm (e.g., about 1.5 mm, about 2 mm, about 2.5 mm, about 3 mm,about 3.5 mm, about 4 mm, about 4.5 mm, about 5 mm, ranges between suchvalues, etc.) or about 1.8 mm² to about 19.6 mm² (e.g., about 1.8 mm²,about 3.1 mm², about 4.9 mm², about 7.1 mm², about 9.6 mm², about 12.6mm², about 15.9 mm², about 19.6 mm², ranges between such values, etc.))for positioning below the knee, about 4 mm to about 10 mm (e.g., about 4mm, about 5 mm, about 6 mm, about 7 mm, about 8 mm, about 9 mm, about 10mm, ranges between such values, etc.) or about 12.6 mm² to about 78.5mm² (e.g., about 12.6 mm², about 19.6 mm², about 28.3 mm², about 38.5mm², about 50.3 mm², about 63.6 mm², about 78.5 mm², ranges between suchvalues, etc.)) for positioning above the knee, etc.). For anotherexample, the third cell pattern may be less dense than the first cellpattern and/or the second cell pattern. For yet another example, thethird cell pattern may comprise fewer struts than the first cell patternand/or the second cell pattern. The reduced amount of metal in the thirdcell pattern makes the third segment easier to puncture to form thewindow 5343 in the graft 5349. The third cell pattern may improvehemodynamics (e.g., because less metal is in the flow path shown by thearrow 5112. The first cell pattern may be the same as or different fromthe second cell pattern. For example, the first cell pattern may have aradial force and/or flexibility configured for placement in an arteryand/or the second cell pattern may have a radial force and/orflexibility configured for placement in a vein. The third segment 5344may be flexible, for example suitable for taking a bend and/or placementin a challenging biomechanical region, (e.g., popliteal, SFA, etc.). Insome implementations, the third cell pattern comprises deformableregions with improved elongation and/or elastic properties to facilitatefenestration with reduced or no risk of damage when displaced byexpandable member.

The stent structure 5348 and/or the graft 5349 may comprise one or moreradiopaque markers 5347 to demarcate the transition between the firstsegment 5342 and the third segment 5346 and/or the transition betweenthe second segment 5344 and the third segment 5346. The radiopaquemarker 5347 may be coupled to struts of the stent structure 5348,electroplated to the stent structure 5348, woven through the struts ofthe stent structure 5348, etc. the radiopaque marker 5347 may beradiopaque material incorporated into the graft 5349. The catheter usedto deliver the device may comprise one or more corresponding radiopaquemarkers to facilitate placement.

FIG. 53Di illustrates an example method of in situ formation of anexample device providing fluid flow from a first vessel to a secondvessel and through the first vessel. The device allows at least someblood to continue to flow in the first vessel, and may provide one ormore of the distal arterial flow preservation advantages describedherein. The device may share several of the features of the device 5300,but is not manufactured with windows or structure such as slitsconfigured to form windows. In FIG. 53Di, a preliminary device 5360 isanchored in the first vessel, extends through interstitial tissue, and(not shown) is anchored in a second vessel. In this way, the preliminarydevice 5360 shares many features with many fistula prostheses describedherein, and any such prostheses may be used as the preliminary device5360.

FIG. 53Di shows an example fenestration device including an expandablemember 5362 (e.g., balloon, temporary stent, etc.), a tapered segment5364, and a puncturer 5366. The expandable member 5362 is configured tocenter the device in the vessel and/or to stabilize the device duringthe application of a fenestration formation force. The expandable member5362 may comprise, for example, a balloon, a stent mesh, supportivearms, etc.

The tapered segment 5364 is configured to stabilize the puncturer 5366during the application of a fenestration formation force and/or to betracked over the puncturer 5366 to expand the window formed by thepuncturer 5366. The tapered segment 5364 may include features similar tothe CXI® support catheter, available from Cook. The tapered segment 5364is optionally longitudinally movable relative to the expandable member5362.

FIG. 53Dii shows an example tapered segment 5374 usable with the deviceof FIG. 53Di. The tapered segment 5374 comprises an angle 5375. When thepuncturer 5366 exits the distal end of the tapered segment 5374, thepuncturer 5366 follows the angle 5375 and continues straight.

FIG. 53Diii shows another example tapered segment 5384 usable with thedevice of FIG. 53Di. The tapered segment 5384 comprises a lumen 5382.The distal end of the lumen 5382 comprises a ramped surface 5383. Whenthe guidewire exits the distal end of the lumen 5382, the guidewire isdeflected by the ramped surface 5383 and extends out of the taperedsegment 5384 at an angle 5385 and continues straight. The taperedsegment 5384 optionally comprises a straight lumen that exits the distalend of the tapered segment 5384, for example selectable by the user foradvancing the guidewire without an angle. The lumen 5382 may comprisedifferent sizes for the angled exit and the straight exit, for exampleand without limitation, 0.018″ (approx. 0.45 mm) for the angled exit and0.014″ (approx. 0.36 mm) for the straight exit).

The tapered segment 5364, 5374, 5384 enters the small opening created bythe puncturer 5366 and expands the hole. The expansion of the hole maycomplete the fenestration, or may make the hole appropriate forreceiving an expandable member. In some implementations, the expandablemember 5362 may be collapsed after serving its anchoring function andthen used to expand the hole. In some implementations, a differentexpandable member may be used to expand the hole.

The puncturer 5366 is configured to puncture the graft of thepreliminary device 5360, for example being relatively stiff, having asharp distal tip, etc. The puncturer 5366 is longitudinally movablerelative to the expandable member 5362 and the tapered segment 5364. Thepuncturer 5366 may comprise a needle or cannula. The puncturer 5366 maycomprise a reentry device. The puncturer 5366 may comprise anatherectomy device, a laser, a guidewire (e.g., distal tip original ormodified (e.g., stiffened and/or sharpened)), etc.

FIGS. 53Ei and 53Eii illustrate an example method of aligning apuncturer 5366 for in situ formation of an example device providingfluid flow from a first vessel 5101 to a second vessel 5102 and throughthe first vessel 5101. The device comprises a radiopaque marker 5390,for example as described herein with respect to the radiopaque marker4210. For example, the marker 5390 may be on one side of a lumen throughwhich a guidewire extends and oriented with respect to the angle of thetapered segment 5374. The marker 5390 may be on the same side as thetaper (e.g., as shown in FIGS. 53Ei and 53Eii). The marker 5390 may beon the opposite side as the taper. The marker 5390 may be parallel tothe taper. As described with respect to the marker 4210, the user mayutilize the crossing plane to know where the puncturer 5366 will piercethe graft. In some implementations, a target 5392 may be positioned inthe first vessel 5101 distal to the device 5360. The target 5392 maycomprise, for example, a guidewire, a marking stent, a biodegradablemarker, contrast (e.g., pooled proximate an occlusion), etc.

FIG. 54A is a side view of yet still another example device 5400providing fluid flow from a first vessel 5101 to a second vessel 5102and through the first vessel 5101. The device 5400 allows at least someblood to continue to flow in the first vessel 5101, and may provide oneor more of the distal arterial flow preservation advantages describedherein. The device 5400 may share several of the features of the device5140 (e.g., the first section 5404 comprising an uncovered stent, thesecond section 5406 comprising a graft, etc.) and/or the device 5320(e.g., the second section 5406 being similar to the device 5320).

The first section 5404 and the second section 5406 of the device 5400are separate and deployed sequentially. For example, the second section5406 may be deployed first. The user may form a window in the secondsection 5406 (e.g., as described with respect to FIGS. 53Bi-53Biii) orthe second section 5406 may be manufactured with a window. The secondsection 5406 ay anchor in the first vessel 5101, extend throughinterstitial tissue, and anchor in the second vessel 5102. The secondsection 5406 allows blood to flow into and through the second vessel5102, as shown by the arrow 5110. The first section 5404 may be deployedsecond, with the distal segment of the first section 5404 extendingthrough the window of the second section 5406. The first section 5404anchors in the first vessel 5101. Blood can flow into the first section5404 and continue to flow in the first vessel 5101, as shown by thearrow 5112. The first section 5404 can provide a predictable and/ordurable fenestration diameter, which may better preserve thefenestration. The stent structure of the first section 5404 is porous,which allows blood to flow into the second section 5406. The proximaland/or distal ends of the first section 5404 and/or the second section5406 may comprise a radiopaque marker 5407, for example to help a userdetermine an anchoring position, an amount of overlap, a rotationalorientation (e.g., if manufactured with the window), etc. Although FIG.54A shows the proximal end of the first section 5404 as being proximalto the proximal end of the second section 5406, the proximal end of thefirst section 5404 may be distal to or aligned with the proximal end ofthe second section 5406. The device 5400 may be considered a bifurcatedstent that is formed in situ. The first section 5404 may be a first legand the second section 5406 may be a second leg.

FIG. 54Bi is a side view of another example device 5410 providing fluidflow from a first vessel 5101 to a second vessel 5102 and through thefirst vessel 5101. The device 5410 allows at least some blood tocontinue to flow in the first vessel 5101, and may provide one or moreof the distal arterial flow preservation advantages described herein.The device 5410 may share several of the features of the device 5400(e.g., the first section 5404 comprising an uncovered stent, the secondsection 5406 comprising a graft, etc.). The device 5410 is manufacturedwith the first section 5414 and the second section 5416 being configuredto bifurcate upon deployment of the device 5410. For example, the distalend of the first section 5414 may be configured (e.g., shape set) toremain straight such that the first section 5414 extends out of a windowin the second section 5416, which curves into the second vessel 5102.For another example, the first section 5414 may comprise a flap coupledto the second section 5416.

FIG. 54Bii is a side view of another example device 5415 providing fluidflow from a first vessel 5101 to a second vessel 5102 and through thefirst vessel 5101. The device 5415 allows at least some blood tocontinue to flow in the first vessel 5101, and may provide one or moreof the distal arterial flow preservation advantages described herein.The device 5415 may share several of the features of the device 5410.The device 5415 comprises a plurality of flaps 5417. The flaps 5417 canreplicate the action of a valve, for example opening (protrudingradially outward) under pulsatile flow. The flaps 5417 can comprisegraft material (e.g., ePTFE). The flaps 5417 can comprise a structurethat acts as a hinge for the radial outward protrusion. The device 5415can maintain a proper amount of blood flow in each vessel 5101, 5102,and others, for example by regulating the flow into the second vessel5102 with excess flow and/or pressure being bled off distal in the firstvessel 5101. The flaps 5417 can be distributed across a proximal segmentof the device 5415 configured to be in the first vessel 5101 (e.g., asshown in FIG. 54Bii). The flaps 5417 that appose a vessel wall would notopen, but the flaps 5417 that are in a bend of the device 5415 couldopen. Flaps 5417 that are proximate a branch vessel of the first vessel5101 could also open to preserve flow into that branch vessel.

FIG. 54C is a side view of yet another example device 5420 providingfluid flow from a first vessel 5101 to a second vessel 5102 and throughthe first vessel 5101. The device 5420 allows at least some blood tocontinue to flow in the first vessel 5101, and may provide one or moreof the distal arterial flow preservation advantages described herein.The device 5420 comprises a first section 5424 and a second section5426. The second section 5426 may share several features of the secondsection 5406 of the device 5400 (e.g., a graft and a window 5423). Thesecond section 5426 may comprise two windows 5423, one having a similarfunction to the window 5323 of the device 5320 (e.g., allowing blood tocontinue to flow in the first vessel 5101) and one having a similarfunction to the window of the second section 5406 of the device 5400(e.g., configured to have the first section 5424 extend therethrough).The second section 5426 may have a single elongate window 5423 thatserves both functions. The first section 5424 and the second section5426 may be separate. For example, the first section 5424 may extendthrough a side of the second section 5426 (e.g., as described withrespect to the device 5400), then anchor in a branch vessel 5425,allowing blood to flow into the device 5420 and through the branchvessel 5425, as shown by the arrow 5114. The first section 5424 maycomprise a stent structure to anchor the first section 5424 in thebranch vessel 5425. Anchoring the first section 5424 in the branchvessel 5425 can help to anchor and position the entire device 5420. Thefirst section 5424 may comprise a graft to help guide blood into thebranch vessel 5425. The device 5420 may lack the first section 5424, inwhich case blood could flow through the window 5423 into the branchvessel 5425. The first section 5424 and the second section 5426 may bemonolithic with the first section 5424 configured to extend from thesecond section 5426, for example as described with respect to the device5410. The second section 5426 may lack the window 5423 and the firstsection 5424 may comprise the window 5423. No matter the preciseconfiguration, the device 5420 maintains fluid flow from the firstvessel 5101 into the branch vessel 5425, as shown by the arrow 5114, andthrough the first vessel 5101, as shown by the arrow 5112, and alsodiverts fluid flow into the second vessel 5102, as shown by the arrow5110.

The devices described herein can be self-expanding, for examplecomprising shape memory (e.g., superelastic) material that expands uponrelease from a catheter. The devices described herein can be balloonexpandable. For example, if placement accuracy of the device isimportant, such as at a crossing point of the fistula or near abifurcation, a balloon expandable device can be expanded only whenrotationally and/or longitudinally positioned as desired.

FIG. 55A is a side view of still another example device 5500 providingfluid flow from a first vessel to a second vessel and through the firstvessel. FIG. 55B shows the device 5500 of FIG. 55A positioned in a firstvessel 5101, extending through interstitial tissue, and into a secondvessel 5102. The device 5500 does not or only slightly protrudes intothe first vessel 5101. Blood flowing through the first vessel 5101 cancontinue to flow in the first vessel 5101, as shown by the arrow 5112.Blood flowing through the first vessel 5101 may also be diverted intothe second vessel 5102, as shown by the arrow 5110. The device 5500allows at least some blood to continue to flow in the first vessel 5101,and may provide one or more of the distal arterial flow preservationadvantages described herein. The device 5500 may share several of thefeatures of the other devices disclosed herein (e.g., a stent structure,a graft, etc.). The device 5500 comprises a stent with flares oranchoring features 5502 configured to anchor the device 5500 in thefirst vessel 5101 and an elongate section 5504 configured to extendthrough interstitial tissue and into the second vessel 5102. The device5500 may comprise one flare 5502 or a plurality of flares 5502 (e.g.,two flares 5502 as shown in FIG. 55A). The flares 5502 could be coveredor uncovered. The elongate section 5504 is preferably covered. Thedevice 5500 may include a laser cut stent, a woven stent, or acombination thereof, for example as described herein. The flares 5502and the elongate section 5504 are substantially symmetrical such thatrotational alignment of the device 5504 is not needed. In someimplementations, a length of the flares 5502 is approximately half ofthe diameter of the flares 5502, which can help to secure the device5500 against the first vessel 5101. The flares 5502 of the device 5500are generally annular.

FIG. 55C shows yet still another example device 5520 providing fluidflow from a first vessel 5101 to a second vessel 5102 and through thefirst vessel 5101. Blood flowing through the first vessel 5101 cancontinue to flow in the first vessel 5101, as shown by the arrow 5112.Blood flowing through the first vessel 5101 may also be diverted intothe second vessel 5102, as shown by the arrow 5110. The device 5520allows at least some blood to continue to flow in the first vessel 5101,and may provide one or more of the distal arterial flow preservationadvantages described herein. The device 5520 may share several of thefeatures of the device 5500 (e.g., flares or anchoring features 5522, anelongate section 5524, etc.). FIG. 55D is a distal end view of thedevice 5520 of FIG. 55C implanted in the first vessel 5101 and thesecond vessel 5102. The flares 5520 appose a sidewall of the firstvessel 5101. The elongate section 5524 apposes sidewalls of the secondvessel 5102.

FIG. 55Ei is a top view of a device 5520 a sharing features of thedevice 5520 of FIGS. 55C and 55D. The device 5520 a comprises fourflares 5522 a projecting radially outward. The flares 5522 a aresymmetrical about the device 5520 a. The flares 5520 a each projectradially outward by about a radius of the device 5520 a. The flares 5520a are wires or struts formed into an arc shape. Such a shape may provideatraumatic anchoring, although tips of the arcs may penetrate or deformthe vessel wall.

FIG. 55Eii is a top view of another device 5520 b sharing features ofthe device 5520 of FIGS. 55C and 55D. The device 5520 b comprises fourflares 5522 b projecting radially outward. The flares 5522 b aresymmetrical about the device 5520 b. The flares 5520 b each projectradially outward by about half a radius of the device 5520 a. The flares5520 b are solid material (e.g., struts cut into the illustrated shape).More material may provide a same amount of anchoring with less length.

FIG. 55F shows yet still another example device 5530 providing fluidflow from a first vessel 5101 to a second vessel 5102 and through thefirst vessel 5101. The device 5530 allows at least some blood tocontinue to flow in the first vessel 5101, and may provide one or moreof the distal arterial flow preservation advantages described herein.The device 5530 may share several of the features of the device 5520(e.g., flares or anchoring features 5532, an elongate section 5534,etc.).

FIG. 55G is a top view of the device 5530 of FIG. 55F. The device 5530comprises six flares 5532 projecting radially outward. The flares 5532are asymmetrical or eccentric about the device 5530. Some of the flares5532 are longer than other flares. Referring again to FIG. 55F, thelonger flare(s) 5532 may be oriented distally in the first vessel 5101,which can provide an opposition force to a direction of blood flow.

FIG. 56A is a side view of still another example device 5600 providingfluid flow from a first vessel 5101 to a second vessel 5102 and throughthe first vessel 5101. The device 5600 allows at least some blood tocontinue to flow in the first vessel 5101, and may provide one or moreof the distal arterial flow preservation advantages described herein.The device 5600 may share several features with the prosthesis 540 ofFIG. 25C (e.g., a plurality of filaments woven into a woven structure,different porosity longitudinal sections, etc.).

The prosthesis 540 comprises an embodiment comprising a low porosityfirst longitudinal section 544 and a high porosity second longitudinalsection 546, with other longitudinal sections also possible. The device5600 may be considered a variation on the prosthesis 540. The device5600 comprises a first section 5604, a second section 5606, and a thirdsection 5608 between the first section 5604 and the second section 5606.The first section 5604 has a low porosity, for example low enough todivert flow such as in a flow diverting stent, as described herein. Thesecond section 5606 has a low porosity, for example low enough to divertflow such as in a flow diverting stent as described herein. The firstsection 5604 and/or the second section 5606 direct blood to flow fromthe first vessel 5101 into the second vessel 5102, as shown by the arrow5110. The first section may have higher porosity. The third section 5608has a porosity that allows blood to continue to flow in the first vessel5101, as shown by the arrow 5112. The device 5600 may be woven (e.g., asshown in FIG. 56 ). Changes in weave parameters (e.g., braid angle, wirecount, etc.) may cause different porosities. The device 5600 maycomprise cut struts (e.g., having different cell patterns or otherparameters to change porosity). Compared to known flow diverting stentsthat are placed in neurovasculature, the device 5600 has a largerdiameter (e.g., as described for the fistula prostheses describedherein) and/or have a conical or tapered shape (e.g., as described forthe fistula prostheses described herein). In embodiments in which thedevice 5600 is woven, the filaments may be larger than neurovascularflow diverting stents (e.g., between about 50 μm and about 100 μm),which can provide durability sufficient to withstand higher flow andpressures associated with peripheral arterial blood flow. Flow divertingstructures may be suitable for any of the sections described herein ascomprising a graft. The porosity of the device 5600 may permitstent-in-stent deployment, for example for long pathways in interstitialtissue.

FIG. 56B is a graph showing flow through a parent vessel and a sidebranch with and without a device 5600 of FIG. 56A for different valuesof porosity of the device 5600. The flow rate for the pre-operation sidebranch is shown by the left-pointing outlined triangle 5610, which isabout 0.18 mL/s. The flow rate for the pre-operation distal parent isshown by the right-pointing outlined triangle 5612, which is about 0.2mL/s. Since the pre-operation points 5610, 5612 do not include a device5600, the porosity of the absent device 5600 may be considered 100%. Theflow rate for the post-operation side branch is shown by theleft-pointing filled triangles 5614. The flow rate for thepost-operation distal parent is shown by the right-pointing filledtriangles 5616. The highest porosity tested was about 89%, whichincreased the flow in the distal parent to about 0.22 mL/s and reducedthe flow in the side branch to about 0.16 mL/s. The lowest porositytested was about 35%, which increased the flow in the distal parent toabout 0.32 mL/s and reduced the flow in the side branch to about 0.07mL/s. The lower the porosity, the more flow is diverted away from theside branch and to the distal parent, with an inflection point at about60%. Thus, the porosity of some or all of the device 5600 and/or thedevices described below for directing flow below an ankle, can beselected based on a desired amount of flow diversion.

FIG. 57A illustrates an example device 5700 for directing flow below anankle. The device 5700 may be a flow focalizing stent configured topreferentially direct flow through a lumen of the device 5700. Thedevice 5700 may reduce, inhibit, or prevent steal in veins distal to adirection of reversed blood flow (reversed relative to normal blood flowin veins), for example in a percutaneous deep venous arterializationcircuit. Certain features of woven devices described herein, for examplethe devices 500, 520, 540, may be incorporated into the device 5700.

As discussed herein, one potential advantage to venous arterializationis improving perfusion of oxygenated to the extremities such as thedistal foot. Lining veins with devices such as stent grafts (e.g., thestent grafts 1132 described herein) can help to direct flow towards anextremity, but due to current mechanical limitations, stent grafts aregenerally not indicated for use in smaller vessels or in vessels thatexperience large mechanical forces. The device 5700 has a design that isrobust and flexible enough to withstand biomechanical forces and flex atthe ankle. Branch vessels distal to the stent grafts can stealoxygenated blood that is intended to be driven to the distal foot. Nearthe calcaneus or heel bone, for example, there are a large number ofconnecting veins that lead to larger return veins of the leg (e.g.,saphenous vein). A small amount of steal may provide some benefit, forexample maintaining a higher flow rate, which can be better for patency.The device 5700 has a design that is generally drives flow to the distalfoot, but may still provide some perfusion to branch vessels, therebyfine tuning the steal.

The device 5700 comprises a plurality of wires or filaments woventogether in a dense pattern. At least some or all of the filamentscomprise a shape memory material (e.g., a superelastic material such asnitinol, chromium cobalt, etc.). In a deployed state, such material isgenerally better suited to withstand biomechanical forces and maintain alow profile. The filaments may have a diameter or cross-section betweenabout 50 μm and about 100 μm (e.g., about 50 μm, about 60 μm, about 75μm, about 90 μm, about 100 μm, ranges between such values, etc.). Thedevice 5700 may comprise between 16 filaments and 96 filaments (e.g.,about 16 filaments, about 32 filaments, about 48 filaments, about 64filaments, about 96 filaments, ranges between such values, etc.). Thenumber of filaments is preferably even, and more preferably divisible by6 and/or 8.

The device 5700 could have an expanded diameter appropriate forplacement in a vein in an ankle, for example between about 4 mm andabout 8 mm (e.g., about 4 mm, about 5 mm, about 6 mm, about 7 mm, about8 mm, ranges between such values, etc.). In some implementations, theone or both ends of the device 5700 may be flared to have an increaseddiameter, which could help to anchor the device 5700 in the vessel. Thedevice 5700 may be substantially cylindrical in an expanded state (e.g.,as shown in FIG. 57A). The device 5700 may be conical, for exampleconfigured to taper from a first diameter at a distal end to a secondsmaller diameter at a proximal end. As opposed to conical stents thatmay be placed in an artery that reduce in size from proximal to distal,the device 5700 may increase in size from proximal to distal, forexample to correspond to the anatomy of the vein, which increases insize towards the heart. The change in diameter may be, for example,between about 2 mm and about 9 mm (e.g., about 2 mm, about 3 mm, about 4mm, about 5 mm, about 6 mm, about 7 mm, about 8 mm, about 9 mm, rangesbetween such values, etc.). For a device 5700 placed below the knee, thechange in diameter may be, for example, between about 3 mm and about 6mm (e.g., about 3 mm, about 4 mm, about 5 mm, about 6 mm, ranges betweensuch values, etc.). The device 5700 may have a length between about 50mm and about 150 mm (e.g., about 50 mm, about 75 mm, about 100 mm, about125 mm, about 150 mm, ranges between such values, etc.).

Porosity between about 60% and about 78% is known to be useful for flowdiverting neurovascular stents to divert blood from aneurysms but permitperfusion to branch vessels. The porosity of the device 5700 may be lessthan 78%, or more preferably less than 60%, to inhibit perfusion tobranch vessels. For flow preservation, porosity in the range of about60% and about 75% is a “sweet spot” allowing for adequate preservationof flow across a bifurcation. Porosity less than about 50% candramatically reduce flow in a bifurcating vessel.

Pore size may also influence hemodynamics. For example, higher picks perinch (PPI) can result in smaller pore size, which can decrease flow intoan aneurysm or a branch vessel, and lower PPI can result in a largerpore size, which can allow perfusion into branch vessels. PPI reflectsan amount of filament material exists in a square inch (approx. 6.5 cm²)of the device 5700. The PPI may range from about 50 PPI to about 500PPI, (e.g., about 50 PPI, about 100 PPI, about 150 PPI, about 200 PPI,about 300 PPI, about 400 PPI, about 500 PPI, ranges between such values,etc.).

In some implementations, the device 5700 may comprise a higher porosityand graft material. For example, the device 5700 may comprise a highflexibility laser cut pattern with a polymer covering. Certain suchdesigns may include a perforated or perforatable covering. The device5700 is different from neurovascular flow diverting stents in a numberof meaningful ways. For example, the device 5700 has a larger diameter,has a larger delivery profile (e.g., greater than 3 Fr), has a longerlength, is tapered to be larger towards the heart, has less porosity,has a higher radial force, and/or has a higher compression resistance,any one of which would be contraindicated for neurovasculature.

The filaments of the device 5700 are woven together to have a high braidangle, which can provide a high radial force. For example, the braidangle may be between about 120° and about 179°, (e.g., about 120°, about130°, about 140°, about 150°, about 160°, about 170°, about 179°, rangesbetween such values, etc.). Compression resistance may be, for example,between about 0.4 N/mm and about 1.1 N/mm (e.g., about 0.4 N/mm, about0.5 N/mm, about 0.6 N/mm, about 0.7 N/mm, about 0.8 N/mm, about 0.9N/mm, about 1 N/mm, about 1.1 N/mm, ranges between such values, etc.).As a basis of comparison, a resistive force of about 1 N/mm may bestrong enough to prop open a valve. Chronic outward force may be, forexample, between about 0.25 N/mm and about 0.6 N/mm (e.g., about 0.25N/mm, about 0.3 N/mm, about 0.35 N/mm, about 0.4 N/mm, about 0.45 N/mm,about 0.5 N/mm, about 0.55 N/mm, about 0.6 N/mm, ranges between suchvalues, etc.). These force values can vary, for example, based on wirediameter and braid angle. A larger wire diameter has a higher radialforce than a smaller wire diameter (e.g., 76 μm can be about 2 N/mmwhile 50 μm can be about 1 N/mm). In some implementations, the radialforce is sufficient to prop open venous valves, which may or may nothave been disabled (e.g., by a cutting device, balloon, etc.). In someimplementations, the radial force is sufficient to expand the vein,which is generally flexible, which can provide a dimensionally knownfluid flow channel.

The ends of the filaments of the device 5700 may be truncated as thedevice 5700 is cut to length. The filaments are small enough that thereis low risk of puncturing the vein or causing issues with fluid flow. Alimited amount of puncturing by free filament ends may help to anchorthe device 5700 in place. In some implementations, the ends of thefilaments may be treated, such as by bending, coiling, welding, couplingto end treatment devices, back-braided, etc.

FIG. 57Bi illustrates a first example of blood flow through a vein 5701proximate to an ankle. A vein 5701 (e.g., posterior tibial vein) islined with a stent graft 1132, for example as described herein. Thestent graft 1132 only extends to approximately the position of theankle, as shown by the dashed line. Blood flowing through the vein 5701can continue towards the foot and the lateral plantar network, as shownby the arrow 5712. However, blood flowing through the vein may be stolenby the branch vessel 5703 (e.g., calcaneal perforator), as shown by thearrow 5714, such that the foot may not be properly perfused.

FIG. 57Bii illustrates a second example of blood flow through a veinproximate to an ankle. Like FIG. 57Bi, the vein 5701 is lined with astent graft 1132 that only extends to approximately the position of theankle. In FIG. 57Bii, the device 5700 is positioned below the stentgraft 1132 in the ankle. Blood flowing through the vein 5701 cancontinue towards the foot and the lateral plantar network, as shown bythe arrow 5712. Blood flowing through the vein may not be stolen by thebranch vessel 5703 because the device 5700 diverts flow away from thevessel 5703. As such, the foot may be better perfused than without thedevice 5700. The device 5700 may be deployed from the foot (e.g., usinga guidewire extending from the foot as described herein) and/or fromfemoral access. The device 5700 may longitudinally overlap with thestent graft 1132. For example, the device 5700 may be radially outwardof the stent graft 1132. In certain such implementations, the device5700 may be deployed before the stent graft 1132.

FIGS. 57Ci-57Ciii illustrate example variations on woven flow divertingdevices 5720, 5730, 5740 sharing features with the device 5700 of FIG.57A. The devices 5720, 5730, 5740 each have a wire diameter of 75 μm anda nominal braid angle of 140°, but have different porosities whenexpanded to different diameters. The device 5720 of FIG. 57Ci has adiameter of 5.5 mm and a porosity of 44%. The device 5730 of FIG. 57Ciihas a diameter of 5 mm and a porosity of 72%. The device 5740 of FIG.57Ciii has a diameter of 4.5 mm and a porosity of 83%. Depending on theamount of oversizing of the device, different porosity can be achieved.Varying the amount of porosity can allow a user to tune the amount ofpermitted steal. Generally, more oversized devices can permit moresteal. Referring again to FIG. 56B, the device 5720 can increase theflow in the distal parent to about 0.31 mL/s and to decrease the flow inthe branch vessel to about 0.08 mL/s; the device 5730 can increase theflow in the distal parent to about 0.26 mL/s and to decrease the flow inthe branch vessel to about 0.13 mL/s; and the device 5740 can increasethe flow in the distal parent to about 0.23 mL/s and to decrease theflow in the branch vessel to about 0.16 mL/s.

FIG. 57Di illustrates a device 5750 in which a portion 5752 of the graftcovering 5759 is perforated with a plurality of openings, controlled insize, to achieve a certain level of porosity to manage flow through thegraft covering. In some implementations, the entire graft covering 5759may be perforated. The openings may be created with laser processing,mechanical perforation, as part of a covering process (e.g., ePTFEsintering), composite assembly of ePTFE with porous membrane, etc. Theshape, size, and/or pattern of the openings may be selected as desired.The pore size should be large enough to allow desired blood flow.

FIG. 57Dii is a schematic side view of the device 5750 of FIG. 57Dishowing the effect of the porous region on fluid flow. A selected amountof fluid can flow through the porous region 5752, for example to abranch vessel, as shown by the arrow 5714. A remainder of fluid can flowto the distal parent, as shown by the arrow 5712. The device 5750 canalso or alternatively be used in a fistula to direct flow from a firstvessel to a second vessel and to maintain a selected amount of flow inthe first vessel.

FIG. 57E is a schematic spectrum of porosity showing the effect ofporosity on steal. The spectrum ranges from 0% porosity (a covered stentwithout any pores) to 100% porosity (no stent). From a porosity of about0% to about 50%, the device effectively prevents steal. Between aporosity of about 60% and about 75%, flow preservation is achieved.Greater than about 86% porosity, little or no flow diversion isachieved.

FIG. 57Fi is a side view of another example device 5760 configured toprovide fluid flow from a first vessel to a second vessel and throughthe first vessel. FIG. 57Fii is an expanded view of the device 5760 of57Fi in the area 57Fii. The device 5760 may share several of thefeatures of the other devices disclosed herein (e.g., a stent structure,a graft, etc.). The device 5760 comprises a plurality of slits 5762,which are easier to see in FIG. 57Fii. The device 5760 is shown in FIG.57Fi is in a straight configuration such that the slits 5762 are in aclosed configuration.

FIG. 57Fiii shows the device 5760 positioned in a first vessel 5101,extending through interstitial tissue, and into a second vessel 5102.FIG. 57Fii is an expanded view of the device 5760 of 57Fiii in the area57Fiv. Blood flowing through the first vessel 5101 can continue to flowin the first vessel 5101, as shown by the arrow 5112. Blood flowingthrough the first vessel 5101 may also be diverted into the secondvessel 5102, as shown by the arrow 5110. The device 5760 allows at leastsome blood to continue to flow in the first vessel 5101, and may provideone or more of the distal arterial flow preservation advantagesdescribed herein. When the device 5760 is flexed due to the bend towardsthe second vessel, the slits 5762 o on the outside of the bend arespread open, while the slits 5762 c on the inside of the bend arecompressed together and the slits 5762 c proximal and distal to the bendremain closed. The open slits 5762 c allow blood to flow through thedevice 5760, as indicated by the arrows 5112, as best seen in FIG.57Fiv.

FIG. 58A is a side view of an example occlusive implant 5800. FIGS.58Bi-58Biii illustrate an example method of in situ coupling of theocclusive implant 5800 and an example device providing fluid flow from afirst vessel 5101 to a second vessel 5102 and through the first vessel5101. FIG. 58Biii shows the implant 5800 and a device 5810 as part of anocclusive system that allows at least some blood to continue to flow inthe first vessel 5101, as shown by the arrow 5112, and may provide oneor more of the distal arterial flow preservation advantages describedherein. The implant 5800 can inhibit or prevent the stealing of arterialblood in the venous return to the heart.

Because blood may have originally been flowing in the second vessel 5102from right to left (e.g., if the second vessel 5012 is a vein) prior toarterialization after which the blood flows from left to right, asindicated by the arrow 5110, and/or because access to the second vessel5102 (e.g., via a targeting system, a snare system, a system to deploythe device 5800, etc.) may have been from the right side, discussions ofproximal, distal, upstream, downstream, etc. can be confusing such thatreference may be made to the left and right with respect to FIGS.58A-58Biii.

The implant 5800 comprises a first part 5802. The first part 5802comprises an occlusive implant. The first part 5802 is configured toocclude the second vessel 5102 to the left of a fistula prosthesis(e.g., the device 5810). The occlusive implant may include, for example,but not limited to, an expandable mesh, a sponge, a plug (e.g.,Amplatzer®, available from Abbott, MVP™, available from Medtronic), acoil or plurality of coils (e.g., Concerto™, available from Medtronic,Interlock™ and VortX®, available from Boston Scientific, AZUR®,available from Terumo, MReye®, available from Cook), an embolic liquid(e.g., Onyx®, available from Medtronic), hydrogel (e.g., Bead Block™available from Boston Scientific), microspheres (e.g., HydroPearl®,available from Terumo), an implantable balloon, combinations thereof,etc. Any system or method that occludes the second vessel 5102 to theleft of a fistula prosthesis may be suitable for the first part 5802.

The implant 5800 optionally comprises a second part 5804 coupled to thefirst part 5802. The second part 5804 comprises a coil or other anchorconfigured to attach the first part 5802 to a fistula prosthesis (e.g.,the device 5810). The second part 5804 can inhibit the first part 5802from drifting to the left. The second part 5804 may be omitted if, forexample, there is low likelihood that the first part 5802 will drift tothe left or become dislodged. If the second vessel 5102 is a vein, thepath to the left goes to the heart, so downstream release of anembolization device should be avoided.

In FIG. 58Bi, the device 5810 is positioned in the first vessel 5101,through interstitial tissue, and into the second vessel 5102, forexample as described herein. The device 5810 may comprise an uncoveredstent that allows blood to flow through pores to the right of FIG. 58Bi,as shown by the arrow 5112. Other fistula flow devices, for example asdescribed herein, can be used in conjunction with the implant 5800. Forexample, if the device 5120 is deployed too far to the right in FIG.51B, there may be a blood flow path to the left of the second vessel5102. The implant 5800 can help to close such blood flow path.

FIG. 58Bi also shows a guidewire 5812 extended through the device 5810in the second vessel 5102. The guidewire 5812 may be used to deploy theimplant 5800. In FIG. 58Bii, the first part 5802 if the implant 5800 isdeployed in the second vessel 5102. The first part 5802 is tethered tothe second part 5804, which is then exposed by withdrawal of a catheter5814, as indicated by the arrow 5816. The second part 5804 may uncoil asit is released from the catheter 5814. The uncoiling of the second partoccurs inside the device 5810 such that the second part 5804 anchorsagainst an inner sidewall of the device 5810 and applies a pulling forceon the first part 5802.

FIG. 58C is a side view of an example occlusive implant systemcomprising the implant 5800. The system also comprises the device 5810.Blood can flow through the device 5810 in the first vessel 5101, asshown by the arrow 5112. Blood can also flow into the device 5810 fromthe first vessel 5101, through interstitial tissue, and to the right inthe second vessel 5102, as shown be the arrow 5110. Blood that flowsinto the device 5810 from the first vessel 5101, through interstitialtissue, and attempts to flow to the left in the second vessel 5102, asshown be the arrow 5118, is stopped by the first part 5802.

The fistula prostheses described herein, for example but not limited tothe devices 5100, 5120, 5140, 5200, 5220, 5230, 5240, 5300, 5320, 5400,5410, 5420, 5600, 5810, can preserve flow through the first vessel. Thedevice may have a variable cell geometry to suit the mechanicalrequirements of the disease state and/or increase flow where needed. Forexample, larger cells may be provided in the region of fenestrationand/or proximate a bifurcation. For another example, smaller cells atthe ends can aid in deployment accuracy and/or wall apposition.Radiopaque markings can aid in rotational and/or longitudinal alignment,for example to provide a user with an indication of where the coveringbegins. Delivery systems may be configured to rotate the device toposition the fenestration such that blood flow through the first vesselis preserved. Additional devices can be provided in a system, forexample to aid in creating fenestrations, placing an occlusive implant,etc.

Referring again to FIGS. 52Ci and 52Cii as an example applicable to thefistula prostheses described herein, including but not limited to thedevices 5100, 5120, 5140, 5200, 5220, 5230, 5240, 5300, 5320, 5400,5410, 5420, 5600, 5810, if the diameter of the first vessel 5101 is Xmm, the diameter of the second section 5236 (e.g., the proximal end ofthe second section 5236) may be between about 0.25X and about 0.75X(e.g., about 0.25X, about 0.35X, about 0.4X, about 0.45X, about 0.5X,about 0.6X, about 0.75X, ranges between such values, etc.). The ratiomay depend, for example, on the diameter X of the first vessel 5101, thediameter of the second vessel 5102, the amount of occlusion in the firstvessel 5101, the position in the first vessel 5101 (e.g., the ratiogenerally being smaller upstream because more branch vessels downstreamof the first vessel 5101 are still supplied), the type of prosthesis,etc. The prostheses may be provided as a suite of prostheses from whicha user may select a desired ratio.

FIG. 59Ai illustrates a third example of blood flow through a vein 5901proximate to an ankle. The vein 5901 (e.g., posterior tibial vein) islined with a stent graft 1132, for example as described herein. Thestent graft 1132 only extends to approximately the position of theankle. Blood flowing through the vein 5901 can continue towards the footand the lateral plantar network. The distal outflow transition to thevein at the distal end 1903 of the stent graft 1132 is not controlled,which can result in sudden transitions in the flow path, which couldincrease the risk of turbulence.

FIG. 59Aii illustrates a fourth example of blood flow through a vein5901 proximate to an ankle. Like FIG. 59Ai, the vein 5901 is lined witha stent graft 1132 that only extends to approximately the position ofthe ankle. In FIG. 59Aii, a device 5900 is positioned below the stentgraft 1132 in the ankle. Blood flowing through the vein 5901 cancontinue towards the foot and the lateral plantar network. The use ofthe device 5900 can control the transition from the distal end 5903 ofthe device 1132 to inhibit or prevent diameter and angle changes thatmay be detrimental to flow.

FIG. 59B illustrates the device 5900 of FIG. 59Aii overlapping a stentgraft 1132. The device 5900 comprises an overlap portion 5902 and atapered portion 5904. The overlap portion 5902 may be cylindrical,tapered, and/or a combination thereof. In some implementations, theproximal end of the device 5900 comprises a radiopaque marker 5912 andthe distal end of the stent graft 1132 comprises a radiopaque marker5914. When the marker 5912 is upstream of the marker 5914, the user canbe assured that the device 5900 overlaps the stent graft 1132 to achievethe desired flow effects. The device 5900 and/or the stent graft 1132may comprise another radiopaque marker to ensure an appropriate amountof overlap (e.g., demarcating the start of the tapered portion 5904).

The tapered portion 5904 tapers from a first diameter 5906 to a seconddiameter 5908 less than the first diameter 5906. The first diameter 5906may be, for example, between about 2 mm and about 10 mm (e.g., about 2mm, about 3 mm, about 4 mm, about 5 mm, about 6 mm, about 7 mm, about 8mm, about 9 mm, about 10 mm, ranges between such values, etc.). Thesecond diameter 5908 may be, for example, between about 1 mm and about 8mm (e.g., about 1 mm, about 2 mm, about 3 mm, about 4 mm, about 5 mm,about 6 mm, about 7 mm, about 8 mm, ranges between such values, etc.).The tapered portion 5904 has a length 5910. The length 5910 may be, forexample, between about 5 mm and about 100 mm (e.g., about 5 mm, about 10mm, about 25 mm, about 50 mm, about 75 mm, about 100 mm, ranges betweensuch values, etc.). The device 5900 can be tuned in diameter, length,taper angle, etc. based on, for example, inflow conditions, outflowgeometry, flow rate, pressure, etc. to produce or optimize thepossibility for laminar flow conditions inside and/or distal to thestent graft 1132. For example, specific desired flow rates may bepossible based on the second diameter 5908 and/or pressure in the device5900.

FIG. 60 is a partially transparent view showing certain vasculature of aleft lower leg. The vasculature includes a P3 segment 6002 of thepopliteal artery. The P3 segment 6002 branches into the anterior tibialartery 6004 and the tibioperoneal trunk 6006. The tibioperoneal trunk orTP trunk or TPT 6006 branches into the posterior tibial artery 6008 andthe peroneal artery 6010. The box 6012 shows an example area where theposterior tibial artery 6008 often includes an occlusion. In several ofthe methods described herein, the crossing from the posterior tibialartery 6008 to the posterior tibial vein 4438 is in the area of the box6012, which is proximate to the occlusion 6014. In some implementations,the crossing can be further upstream of the occlusion 6014, for examplein the P3 segment 6002 or the tibioperoneal trunk 6004 or proximal inthe posterior tibial artery 6008 (e.g., spaced from the occlusion 6014).The P3 segment 6002 and the tibioperoneal trunk 6006 are usually largerand less diseased than the posterior tibial artery 6008. Crossing fromthe P3 segment 6002 or the tibioperoneal trunk 6006 or proximal in theposterior tibial artery 6008 can improve inflow to the venousarterialization. The fistula prosthesis can be placed in the P3 segment6002 or the tibioperoneal trunk 6006 with reduced fear of jailing otherarteries. Placement of a fistula prosthesis (e.g., having the ability tomaintain flow in the artery distal to the fistula) upstream of theocclusion can open the procedures described herein to a broader patientpopulation (e.g., high risk patients in addition to no-option patients).Placement of a fistula prosthesis (e.g., having the ability to maintainflow in the artery distal to the fistula) upstream of the occlusion canreduce the risk of steal-induced ischemia with proper management ofblood flow volumes in the fistula prosthesis. Other arteries that can beused for procedures described herein include, but are not limited to,the anterior tibial artery (ATA) and the peroneal or fibular peroneal.The posterior tibial vein 4438 can be targeted, in severalcircumstances, regardless of which vessel is occluded.

The P3 segment 6002 and the tibioperoneal trunk 6006 are major supplyvessels to the lower limb. In seeking to move the artery-vein connectionproximally to the P3 segment 6002 or the tibioperoneal trunk 6006, thereis an increased risk of diverting too much blood from the arterial treegiven their larger diameters and blood volumes. Stealing too much bloodfrom these arteries 6002, 6006 by diverting blood into a vein can leadto ischemia in the tissues they supply. The amount of steal can beinfluenced by several factors such as geometry (diameter, lumen shape),pressure gradients (arterial to venous, other stealing veins distal tothe crossing like the greater saphenous vein), number of available flowpaths, arterial blood supply, and the like. As described herein, someprostheses can divert blood from an artery to a vein and still provideblood flow through the artery distal to the fistula. Although sucharterial flow preserving venous arterialization can maintain blood flowin the artery distal to the artery-vein connection, diverting too muchblood can still be a serious risk.

Controlling the flow in the prosthesis can be important to the health ofthe subject. Specific prosthesis geometry can achieve the desired flowin the arterialized vein. Nominal blood flow in the higher arteries isabout 750 mL/min. Flow rates through arterialized veins described hereincan be between about 50 mL/min and about 500 mL/min, (e.g., about 50mL/min, about 100 mL/min, about 150 mL/min, about 200 mL/min, about 250mL/min, about 300 mL/min, about 350 mL/min, about 400 mL/min, about 450mL/min, about 500 mL/min, ranges between such values, etc.), which hasbeen found to be sufficient to reduce distal limb ischemia. Flow rateshigher than 500 mL/min may also be sufficient (e.g., when the fistulaprosthesis is placed far upstream of an occlusion). Flow rates lowerthan 50 mL/min may also be sufficient (e.g., when the fistula prosthesisis placed far down a leg). A prosthesis diameter between about 2 mm andabout 3.5 mm (e.g., about 2 mm, about 2.5 mm, about 3 mm, about 3.5 mm,ranges between such values, etc.) can provide thus sufficient bloodflow, depending on flow characteristics and anatomy (e.g., resistance orpulling by downstream vessels). If some blood is allowed to continue toflow through the artery, the diverted blood preferably provides similarflow while also enabling proximal crossing locations.

FIG. 61A illustrates an example of a prosthesis 6100 that can be placedupstream of an occlusion. The prosthesis 6100 comprises a first segment6101, a second segment 6102, a third segment 6103, a fourth segment6104, and a fifth segment 6105. The lengths, diameters, and shapes ofthe segments 6101-6105 in FIG. 61A are schematic only. The first segment6101 is configured to anchor in a proximal artery (e.g., the P3 segment6002 or the tibioperoneal trunk 6006). The first segment 6101 isconfigured to span interstitial tissue between the artery and a vein.The fifth segment 6105 is configured to anchor in a proximal vein. Thethird segment 6103 is preferably configured to reside in the vein. Thethird segment 6103 is narrower than the first segment 6101. The secondsegment 6102 tapers from the first segment 6101 to the third segment6103. The third segment 6103 is preferably narrower than the fifthsegment 6105 (e.g., as shown in FIG. 61A), which can provide betterhemodynamics than terminating the prosthesis 6100 at the third segment6103 or positioning the third segment 6103 too close to one end. Thefourth segment 6104 tapers from the third segment 6103 to the fifthsegment 6105. The fourth segment 6104 and the fifth segment 6105 mayoptionally be omitted.

The narrowness of the third segment 6103 can limit the flow of blood(e.g., by increasing the flow resistance) through the prosthesis 6100.The amount of blood that can flow through the third segment 6103 is lessthan the amount of blood that can flow through the first segment 6101and the fifth segment 6105. The second segment 6102 and the fourthsegment 6104 provide a gentle transition from the arterial diameter tothe third segment 6103 and from the third segment 6103 to the venousdiameter, respectively. Such gentle transitions can help produce laminarflow and/or reduce turbulence in the prosthesis 6100. Overall, theprosthesis 6100 has an hourglass shape. The third segment 6103 does notinclude a balloon. The third segment 6103 does not include a pump. Thethird segment 6103 does not include leaflets or other valve components.The third segment 6103 does not include embolic filtering components.The third segment 6103 is not configured to cause embolization. Thethird segment 6103 does not make up for oversizing of the first segment6101 and/or the fifth segment 6105, which are purposefully sized toanchor in first and second vessels. The narrowing of the third segment6103 is contrary to the teaching of peripheral vascular prosthesesconfigured to prop open the vessel to allow as much blood flow aspossible. Certain elements (such as one or more of the balloon, pump,filter, etc.) are optionally excluded in some embodiments and present inothers.

FIG. 61B illustrates another example of a prosthesis 6120 that can beplaced upstream of an occlusion. The prosthesis 6120 comprises a firstsegment 6121, a second segment 6122, and a third segment 6123. Thelengths, diameters, and shapes of the segments 6121-6125 in FIG. 61B areschematic only. The first segment 6121 is configured to anchor in aproximal artery (e.g., the P3 segment 6002 or the tibioperoneal trunk6006). The first segment 6121 is configured to span interstitial tissuebetween the artery and a vein. The third segment 6123 is preferablyconfigured to reside in the vein. The third segment 6123 is narrowerthan the first segment 6121. The second segment 6122 tapers from thefirst segment 6121 to the third segment 6123. The prosthesis 6120 may besimilar to the prosthesis 6100 with the fourth segment 6104 and thefifth segment 6105 omitted (e.g., then prosthesis 6120 gently taperingdown to a diameter (e.g., about 3.5 mm or about 4 mm) in the secondsegment 6122 and then staying at that diameter in the third segment6123. The narrowness of the third segment 6123 can, for example, providethe prosthesis 6120 with at least some of the benefits of the thirdsegment 6103 of the prosthesis 6100 (e.g., limiting the flow of bloodthrough the prosthesis 6120).

FIG. 61C illustrates yet another example of a prosthesis 6150 that canbe placed upstream of an occlusion. The prosthesis 6150 may shareseveral features of the device 5300, for example a stent structure 6158,graft 6159, radiopaque markers, etc. The prosthesis 6150 may provide theability to provide fluid flow from a first vessel 5101 to a secondvessel 5102, as shown by the arrow 5110, and through the first vessel5101, as shown by the arrow 5112. In the example illustrated in FIG.61C, the first vessel 5101 is the P3 segment 6002, although othervessels are also possible. The prosthesis 6150 allows at least someblood to continue to flow in the first vessel 5101, and may provide oneor more of the distal arterial flow preservation advantages describedherein. The prosthesis 6150 comprises windows or fenestrations 6160lacking the graft 6159. The graft 6159 may be removed to form thewindows 6160, or not formed in the first place, for example as describedherein. The prosthesis 6150 may share several features of the prosthesis6100 such as the shape and order of the segments 6101-6105. For example,the prosthesis 6150 comprises a first segment 6151 anchored in the firstvessel 5101 and extending through interstitial tissue. For anotherexample, the prosthesis 6150 comprises a third segment 6153 in thesecond vessel 5102. The third segment 6153 limits flow through theprosthesis 6150 (e.g., by increasing the flow resistance) and thereforeinto the second vessel 5102. The third segment 6103 does not causeincreased pressure because the third segment 6103 allows excess pressureto dissipate by continuing in the first vessel 5101. This limiting offlow can limit vessel steal. This limiting of flow can also providehemodynamics such that sufficient blood continues to flow in the firstvessel 5101, for example downstream in the vessel 5101 and to a branchvessel 5425. An excess of blood can flow into the first segment, so theangle of the fistula does not affect the amount of blood that is able toflow through the third segment 6103 and therefore into the second vessel5102. Although the combination of the shape of the prosthesis 6100 andcertain features of the device 5100 are shown in FIG. 61C, it will beappreciated that the combination of the shape of the prosthesis 6100 andcertain features of other devices described herein, including but notlimited to the devices 5100, 5120, 5140, 5160, 5200, 5220, 5230, 5240,5300, 5310, 5320, 5360, 5400, 5410, 5415, 5420, 5500, 5520, 5530, 5600,5750, 5760, 5810.

The upstream fistula crossing described herein can be combined withother methods described herein (e.g., radiopaque marker targeting,bifurcation identification, expandable member puncturing, guidewiresnaring, vein lining, valve disabling, pedal access, etc.). For example,a method of placing the prosthesis 6150 may comprise using a radiopaquemarker on a crossing catheter in a first vessel to target a radiopaqueexpandable member in a second vessel, and placing the prosthesis 6150(e.g., using a balloon to expand at least one of the segments6151-6155). The method may comprise puncturing the expandable member inthe second vessel, snaring a guidewire, proximally retracting the snaredguidewire out of the second vessel, and tracking devices such as aprosthesis delivery catheter, vein liner catheter, valve disablingdevice, etc. over the guidewire.

In some implementations, the stent structure 6158 may narrow in thethird segment 6153 and the graft 6159 may follow the curvature of thestent structure 6158 to also narrow in the third segment. Such animplementation may be easier to manufacture, for example.

FIG. 61D illustrates still another example of a prosthesis 6180 that canbe placed upstream of an occlusion. The prosthesis 6180 may sharefeatures of the prosthesis 6150. In FIG. 61D, the stent structure 6188does not narrow in the third segment 6183. Rather than following thecurvature of the stent structure 6188, the graft 6189 narrows within thestent structure 6188 in the third segment 6183.

FIG. 62A illustrates an example of a prosthesis 6200 that can be placedupstream of an occlusion. The prosthesis 6200 comprises a first segment6201, a second segment 6202, a third segment 6203, a fourth segment6204, and a fifth segment 6205. The first segment 6201 is configured toanchor in a proximal artery (e.g., the P3 segment 6002 or thetibioperoneal trunk 6006). The first segment 6201 is substantiallycylindrical. The first segment 6201 has a diameter 6206. The diameter6206 can be, for example, between about 5 mm and about 7 mm (e.g., about5 mm, about 5.5 mm, about 6 mm, about 6.5 mm, about 7 mm, ranges betweensuch values, etc.). The fifth segment 6205 is configured to anchor in aproximal vein. The fifth segment 6205 is substantially cylindrical. Thefifth segment 6205 has a diameter 6207. The diameter 6207 can be, forexample, between about 5 mm and about 7 mm (e.g., about 5 mm, about 5.5mm, about 6 mm, about 6.5 mm, about 7 mm, ranges between such values,etc.). The diameter 6206 can be the same as the diameter 6207.

The third segment 6203 is preferably configured to reside in the vein.The third segment 6203 may be configured to reside in interstitialtissue or at least partially in the artery. The third segment 6203 issubstantially cylindrical. Other geometries that could increase flowresistance are also possible (e.g., oval, slotted, etc.). The thirdsegment 6203 has a diameter 6208. The diameter 6208 can be, for example,between about 2.5 mm and about 5 mm (e.g., about 2.5 mm, about 3 mm,about 3.5 mm, about 4 mm, about 4.5 mm, about 5 mm, ranges between suchvalues, etc.). The diameter 6208 is less than the diameter 6206. Thediameter 6208 may be less than the diameter 6207. The second segment6202 tapers from the diameter 6206 to the diameter 6208. The fourthsegment 6204 tapers from the diameter 6208 to the diameter 6207.

The segments 6121-6125 can be shape set to take the shapes and/ordiameters shown in FIG. 62A. In some implementations, an expansionballoon can be used to shape one or more of the segments 6121-6125. Forexample, slow inflation and longitudinal movement of a balloon or otherexpandable member can form the tapered segments 6122 and/or 6124.

FIG. 62B illustrates another example of another prosthesis 6220 that canbe placed upstream of an occlusion. The prosthesis 6220 is similar tothe prosthesis 6200, except that the diameter 6226 is smaller than thediameter 6227. The diameter 6226 can be, for example, between about 4 mmand about 6 mm (e.g., about 4 mm, about 4.5 mm, about 5 mm, about 5.5mm, about 6 mm, ranges between such values, etc.). The diameter 6227 canbe, for example, between about 5 mm and about 7 mm (e.g., about 5 mm,about 5.5 mm, about 6 mm, about 6.5 mm, about 7 mm, ranges between suchvalues, etc.). The diameter 6228 is smaller than the diameters 6226,6227. The diameter 6228 can be, for example, between about 2.5 mm andabout 5 mm (e.g., about 2.5 mm, about 3 mm, about 3.5 mm, about 4 mm,about 4.5 mm, about 5 mm, ranges between such values, etc.).

FIG. 62C illustrates yet another example of a prosthesis 6240 that canbe placed upstream of an occlusion. The prosthesis 6240 can share somefeatures of the prosthesis 6200, except that the prosthesis 6240 lacksthe first and second segments. The prosthesis 6240 comprises the thirdsegment 6243, the fourth segment 6244, and the fifth segment 6245. Thediameter 6247 of the fifth segment 6245 can be, for example, betweenabout 5 mm and about 7 mm (e.g., about 5 mm, about 5.5 mm, about 6 mm,about 6.5 mm, about 7 mm, ranges between such values, etc.). Thediameter 6248 of the third segment 6243 is smaller than the diameter6247. The diameter 6428 can be, for example, between about 2.5 mm andabout 5 mm (e.g., about 2.5 mm, about 3 mm, about 3.5 mm, about 4 mm,about 4.5 mm, about 5 mm, ranges between such values, etc.). Theprosthesis 6240 may be a modification, for example, of the device 5200,5220, 5230, 5240, etc. where the prosthesis does not necessarilydirectly anchor in the first vessel.

FIG. 62D illustrates still another example of a prosthesis 6260 that canbe placed upstream of an occlusion. The prosthesis 6260 can share somefeatures of the prosthesis 6200, except that the prosthesis 6260 lacksthe second segment. The prosthesis 6260 comprises the first segment6261, the third segment 6263, the fourth segment 6264, and the fifthsegment 6265. The first segment 6261 is configured to anchor in theartery. Rather than the first segment 6261 spanning interstitial tissueand tapering to the third segment 6263, the third segment 6263 extendstransversely from the first segment 6261. The third segment 6263 extendsat least partially through interstitial tissue and may enter the vein.The diameter 6266 of the first segment 6261 can be, for example, betweenabout 5 mm and about 7 mm (e.g., about 5 mm, about 5.5 mm, about 6 mm,about 6.5 mm, about 7 mm, ranges between such values, etc.). Thediameter 6267 of the fifth segment 6265 can be, for example, betweenabout 5 mm and about 7 mm (e.g., about 5 mm, about 5.5 mm, about 6 mm,about 6.5 mm, about 7 mm, ranges between such values, etc.). Thediameter 6268 of the third segment 6263 is smaller than the diameter6267. The diameter 6428 can be, for example, between about 2.5 mm andabout 5 mm (e.g., about 2.5 mm, about 3 mm, about 3.5 mm, about 4 mm,about 4.5 mm, about 5 mm, ranges between such values, etc.). Theprosthesis 6260 may be a modification, for example, of the device 5400,5410, etc. where the prosthesis does not necessarily have a segment thatanchors in the first vessel and then extends through interstitialtissue.

FIG. 63A illustrates an example of a prosthesis 6300 that can be placedupstream of an occlusion. The prosthesis 6300 can share features of theprosthesis 6100 (e.g., the first segment 6301, the second segment 6302,the third segment 6303, the fourth segment 6304, the fifth segment 6305,the diameter 6306, the diameter 6307, the narrow diameter 6308, etc.).The first segment 6301 of the prosthesis 6300 comprises a flange 6310.The illustrated flange 6310 is configured to help the first segment 6301anchor in the artery. The flange 6310 could be additionally oralternatively configured to anchor in the vein and/or interstitialtissue. The flange 6310 can comprise, for example, extensions, loops,struts, arms, times, etc. The flange 6310 can be configured to anchorthe prosthesis 6300 to properly align a fenestrated portion. The flange6310 can allow the prosthesis 6300 to be used in a variety of vesselsand subjects. For example, the flange 6310 can help the first segment6301 to anchor in a P3 segment 6002, a tibioperoneal trunk 6006, or aposterior tibial artery 6008 (e.g., spaced from an occlusion 6014 wherethe posterior tibial artery 6008 is larger, proximate to an occlusion6014 where anchoring may be difficult due to vessel wall irregularity).The flange 6310 has a diameter 6309 greater than the diameter 6306. Thediameter 6309 may be, for example, between about 8 mm and about 12 mm(e.g., about 8 mm, about 9 mm, about 9.5 mm, about 10 mm, about 10.5 mm,about 11 mm, about 12 mm, ranges between such values, etc.). Thediameter 6309 may be, for example, between about 50% and about 90%(e.g., about 50%, about 60%, about 70%, about 80%, about 90%, rangesbetween such values, etc.) greater than the diameter 6306, which mayhave the dimensions of the diameters 6206, 6226 just as all dimensionsdescribed herein may be shared amongst the various devices depending oncontext. The flange 6310 may be integral with the stent structure. Theflange 6310 may be coupled to the first segment 6301. The flange 6310may be in a central part of the first segment 6301 (e.g., as shown inFIG. 63A). The flange 6310 may be proximate to a proximal end of thefirst segment 6301. The flange 6310 may be proximate to a distal end ofthe first segment 6301.

FIG. 63B illustrates another example of a prosthesis 6330 that can beplaced upstream of an occlusion. The prosthesis 6330 can share featuresof the prosthesis 6300 (e.g., the flange 6340). The prosthesis 6330comprises a stent structure 6338 and a graft 6339. The stent structure6338 is illustrated as being a woven structure, although cut struts andcombinations thereof are also possible, for example as described herein.The flange 6340 is integral with the stent structure 6338. The graft6339 is coupled to the stent structure 6338 distal to the flange 6340.The graft 6339 comprises a window 6333 to allow blood to continue toflow in the vessel in which the first segment 6331 is placed. In someimplementations, the flange 6310 spaces the first segment 6331 from thevessel wall such that blood can continue to flow around the firstsegment 6331 so as to continue to flow in the vessel in which the firstsegment 6331 is placed (e.g., as described with respect to the device5240). In certain such implementations, the window 6333 may be omitted.

FIG. 63C illustrates yet another example of a prosthesis 6350 that canbe placed upstream of an occlusion. The prosthesis 6350 can sharefeatures of the prosthesis 6300 (e.g., the flange 6360), except that theprosthesis 6350 does not include a first or second segment. The flange6310 is coupled to the third segment 6353. The flange 6360 may be in acentral part of the third segment 6353. The flange 6360 may be proximateto a proximal end of the third segment 6353 (e.g., as shown in FIG.63C). The flange 6360 may be proximate to a distal end of the thirdsegment 6353. The flange 6360 spaces the third segment 6353 from thevessel wall such that blood can continue to flow around the firstsegment 6353 so as to continue to flow in the vessel in which the thirdsegment 6353 is placed (e.g., as described with respect to the device5240). The narrow third segment 6353 limits the amount of blood that canflow through the prosthesis 6350 into the second vessel.

FIG. 64 illustrates an example of a flow limiting implant 6400. Theimplant 6400 comprises a first segment 6401, a second segment 6402, anda third segment 6403. The first segment 6401 and the third segment 6403are configured to anchor the implant 6400 in the prosthesis and/or thevessel. The second segment 6402 comprises a narrow cylindrical sectionthat can limit flow through the implant 6400, for example as describedwith respect to certain third segments herein. The implant 6400 canprovide the flow limiting benefits to devices that do not have a flowlimiting element, such as described herein or commercially availabledevices that may be suitable for placement in a fistula.

FIG. 65 illustrates still another example of a prosthesis 6500 that canbe placed upstream of an occlusion. The prosthesis 6500 can sharefeatures of the prosthesis 6200, for example comprising a first segment6501, a second segment 6502, a third segment 6503, a fourth segment6504, and a fifth segment 6505. The third segment 6503 comprises aflexible or elastic material, which may be called a flexible venturi ora self-regulating valve. As velocity increases in a fluid, pressuredecreases. Because the third segment 6503 comprises a flexible material,a decrease in pressure draws the walls of the prosthesis inward,effectively reducing the diameter of the third segment. This reductionin diameter can reduce the flow rate, compensating as conditions indistal limb (e.g., foot) change over time (maturation) and/or aremodified (e.g., by intentional occlusion of stealing veins). The thirdsegment 6503 could be fully flexible, for example able to narrow (e.g.,as shown in FIG. 65 ) or widen to the diameter of the first segment 6501and/or the fifth segment 6505. The largest diameter of the third segment6503 could be limited to ensure limited flow under any conditions. Forexample, the maximum diameter of the third segment 6503 could be, forexample, between about 2.5 mm and about 5 mm (e.g., about 2.5 mm, about3 mm, about 3.5 mm, about 4 mm, about 4.5 mm, about 5 mm, ranges betweensuch values, etc.). In some implementations, a rigid stents structurecould limit expansion of the third segment 6503 and a flexible graftstructure could allow narrowing of the third segment 6503.

In some implementations, the devices described herein, including thefenestrated stents (e.g., positioned upstream of orlongitudinally-spaced from an arterial occlusion), may be used in avenous arterialization procedure. In certain such procedures, veinlining stents (e.g., as described herein or other liners) can be placedin the vein. The vein liner can help to prop open venous valves. Thevein liner can close off branch vessels. The vein liner can be placed inthe vein prior to placing a prosthesis in the fistula. The vein linercan overlap with the fistula prosthesis. In some implementations, thedevices described herein, including the fenestrated stents (e.g.,positioned upstream of or longitudinally-spaced from an arterialocclusion), can be used in a percutaneous or surgical bypass procedure.In certain such procedures, a fenestrated stent can be used to extendfrom an artery to a vein (or other appropriate second vessel). A second,non-fenestrated stent, can be used to extend from the vein back into theartery or into another vessel. A liner can be deployed in the bypassvessel, for example between the two fistula prostheses. In certain suchprocedures, a fenestrated stent can be used to extend from an artery toa harvested or artificial vessel. A second, non-fenestrated stent, canbe used to extend from the harvested or artificial vessel back into theartery or into another vessel. A liner can be deployed in the harvestedor artificial vessel, for example between the two fistula prostheses.

Although some example embodiments have been disclosed herein in detail,this has been done by way of example and for the purposes ofillustration only. The aforementioned embodiments are not intended to belimiting with respect to the scope of the appended claims, which follow.It is contemplated by the inventors that various substitutions,alterations, and modifications may be made to the invention withoutdeparting from the spirit and scope of the invention as defined by theclaims. For example, although described herein with respect to alignmentof catheters including a needle, the systems and methods describedherein may be used to align other types of catheters, for example guidecatheters that navigate vasculature including bifurcations, embolicmaterial (e.g., coil) delivery catheters, directional atherectomycatheters, neurostimulation or ablation catheters that should be have arotational orientation to target a nerve, etc. For another example,although described herein with respect vascular catheters, the systemsand methods described herein may be used to align endoscopes,transcutaneous devices, etc. For yet another example, although certainprocedures may be described with respect to a needle crossing from anartery to a vein, crossing from a first artery to a second artery,crossing from a first vein to a second vein, crossing from a vein to anartery, crossing from a first vessel to a second vessel, crossing from afirst cavity to a second cavity, crossing from a cavity to a vessel, andcrossing from a vessel to a cavity are possible.

While the devices described herein may be used in applications in whichthe fluid that flows through the device is a liquid such as blood, thedevices could also or alternatively be used in applications such astracheal or bronchial surgery where the fluid is a gas, such as air. Insome embodiments, the fluid may contain solid matter, for example embolior, in gastric surgery where the fluid includes food particles.

While the invention is susceptible to various modifications, andalternative forms, specific examples thereof have been shown in thedrawings and are herein described in detail. It should be understood,however, that the invention is not to be limited to the particular formsor methods disclosed, but, to the contrary, the invention is to coverall modifications, equivalents, and alternatives falling within thespirit and scope of the various embodiments described and the appendedclaims. Any methods disclosed herein need not be performed in the orderrecited. The methods disclosed herein include certain actions taken by apractitioner; however, they can also include any third-party instructionof those actions, either expressly or by implication. For example,actions such as “making valves in the first vessel incompetent” include“instructing making valves in the first vessel incompetent.” The rangesdisclosed herein also encompass any and all overlap, sub-ranges, andcombinations thereof. Language such as “up to,” “at least,” “greaterthan,” “less than,” “between,” and the like includes the number recited.Numbers preceded by a term such as “about” or “approximately” includethe recited numbers. For example, “about 10 mm” includes “10 mm.” Termsor phrases preceded by a term such as “substantially” include therecited term or phrase. For example, “substantially parallel” includes“parallel.”

1. (canceled)
 2. A method of increasing blood perfusion in a vein in afoot for a venous arterialization procedure, the method comprising:diverting blood flow from an artery to a first vein, diverting bloodfrow from the artery to the first vein comprising creating a fistulabetween the artery and the first vein; accessing a second vein in a footat a location distal to the fistula; disabling one or more valves in thesecond vein to facilitate blood flow distally from the fistula to thesecond vein in the foot, disabling one or more valves comprising:positioning a stent in the second vein; expanding the stent in thesecond vein to open one or more valves in the second vein to reduceinhibition of retrograde blood flow by the one or more valves; andproviding blood flow distally from the artery, through the fistula, andto the foot through the stent in the second vein, providing blood flowdistally comprising permitting blood flow through a sidewall of thestent to permit blood flow to branch vessels located adjacent to thestent.
 3. The method of claim 2, wherein the second vein is acontinuation of the first vein.
 4. The method of claim 2, wherein thestent comprises a bare metal stent.
 5. The method of claim 2, whereinthe stent comprises a drug eluting stent.
 6. The method of claim 2,wherein the stent comprises a polymer stent.
 7. The method of claim 2,wherein the stent comprises a laser cut stent.
 8. The method of claim 2,wherein the stent comprises a diameter between about 2 mm and about 6mm.
 9. The method of claim 2, wherein the second vein comprises alateral plantar vein, a lateral marginal vein, a medial plantar vein, amedial marginal vein, a fibular vein, a dorsal arcade of the foot, or adorsal vein of a Hallux.
 10. A method of increasing blood perfusion in avein in a foot for a venous arterialization procedure, the methodcomprising: diverting blood flow from an artery to a vein, divertingblood frow from the artery to the vein comprising creating a fistulabetween the artery and the vein; disabling one or more venous valves ina foot to facilitate retrograde blood flow from the fistula to the foot,disabling one or more venous valves comprising expanding a stent in thefoot to open the one or more venous valves in the foot to reduceinhibition of retrograde blood flow by the one or more venous valves;and providing retrograde blood flow from the artery, through thefistula, and to the foot through the stent in the foot.
 11. The methodof claim 10, wherein providing retrograde blood flow comprisespermitting retrograde blood flow through a sidewall of the stent topermit blood flow to branch vessels located adjacent to the stent. 12.The method of claim 10, wherein the stent is positioned at a locationdistal to the fistula.
 13. The method of claim 10, wherein the stentcomprises a bare metal stent.
 14. The method of claim 10, wherein thestent comprises a drug eluting stent.
 15. The method of claim 10,wherein the stent comprises a polymer stent.
 16. The method of claim 10,wherein the stent comprises a laser cut stent.
 17. The method of claim10, wherein the stent comprises a diameter between about 2 mm and about6 mm.
 18. The method of claim 10, wherein one or more venous valves arelocated within a lateral plantar vein, a lateral marginal vein, a medialplantar vein, a medial marginal vein, a fibular vein, a dorsal arcade ofthe foot, or a dorsal vein of a Hallux.
 19. The method of claim 10,wherein providing retrograde blood flow comprises permitting retrogradeblood flow through a sidewall of the stent to permit blood flow tobranch vessels located adjacent to the stent, wherein the stent ispositioned at a location distal to the fistula, wherein the stentcomprises a diameter between about 2 mm and about 6 mm, and wherein thestent comprises a bare metal stent.
 20. A method of increasing bloodperfusion in a vein in a foot for a venous arterialization procedure,the method comprising: disabling one or more venous valves in a foot tofacilitate retrograde blood flow in a vein of the foot, disabling one ormore venous valves comprising expanding a stent in the foot to open theone or more venous valves in the foot to reduce inhibition of retrogradeblood flow by the one or more venous valves; and providing retrogradeblood flow to the foot through the stent in the foot.
 21. The method ofclaim 20, wherein providing retrograde blood flow comprises permittingretrograde blood flow through a sidewall of the stent to permit bloodflow to branch vessels located adjacent to the stent.
 22. The method ofclaim 20, wherein providing retrograde blood flow comprises providingretrograde blood flow from a fistula between an artery and a vein and tothe foot through the stent in the foot.
 23. The method of claim 22,wherein the stent is positioned at a location distal to the fistula. 24.The method of claim 20, wherein the stent comprises a bare metal stent.25. The method of claim 20, wherein the stent comprises a drug elutingstent.
 26. The method of claim 20, wherein the stent comprises a polymerstent.
 27. The method of claim 20, wherein the stent comprises a lasercut stent.
 28. The method of claim 20, wherein the stent comprises adiameter between about 2 mm and about 6 mm.
 29. The method of claim 20,wherein one or more venous valves are located within a lateral plantarvein, a lateral marginal vein, a medial plantar vein, a medial marginalvein, a fibular vein, a dorsal arcade of the foot, or a dorsal vein of aHallux.
 30. The method of claim 20, wherein providing retrograde bloodflow comprises: providing retrograde blood flow from a fistula betweenan artery and a vein and to the foot through the stent in the foot,permitting retrograde blood flow through a sidewall of the stent topermit blood flow to branch vessels located adjacent to the stent,wherein the stent is positioned at a location distal to the fistula,wherein the stent comprises a diameter between about 2 mm and about 6mm, and wherein the stent comprises a bare metal stent.